Hi, I would really reccomend trying 'classical' guitar, if you can afford it.
To me its analogous to learning to draw, then paint, then using software to make pictures - its fine to start anywhere, but where you start will shape your understanding of the other media and all aspects of the subject. Like 'brushes' in software are rooted in (although deviate from) brushes in oil or acrylic etc. So, if you start with the basics, you'll more easily develop a more comprehensive understanding of the subject as a whole.
Basically, acoustic (steel string) or electric guitar, with picks or strumming by hand, are not the fundamentals of guitar, but rather so-called 'fingerstyle', that is in our times most commonly using a nylon string (and some metal coated bass strings) 'classical' guitar. All other modern techniques evolve from that (and earlier, the lute I think). Of course, they have their own styles and developments and techniques, but these are not the fundamentals, they're deviations due to developments of the instrument.
Classical guitar is easier to play in some ways, beacuse the strings are softer. A pick, while it can produce complex motions with practice, is not as dextrous as your fingers (again, with practice). A lot of classical sheet music, professionally produced, is available for all levels of skill, sometimes for free because of its age. There are also a lot of styles to try, from all across Europe and European settler states, which incorporate different musical traditions. In my experience, at least where I live, its harder (but not impossible) to find adaptations from the rest of the world however (like East Asia, where they have the lap guitar/harp instead, at least traditionally).
In comparison, its very hard to find 'classic rock' music accurately transcribed, and cheaply, and also its a lot more difficult to translate such music to a single guitar without broad approximations that for me at least make it frustrating to play. That is, a lot of music from that era uses effects that are achievable with a satisfactory level of fidelity only if you have a particular type of guitar, amp, pedals, and studio, or a full band. Further, I think that 'fingerstyle' classical guitar is able to reproduce such sounds better than 'strumming' and even metal string guitars, beacuse its easier, or more achievable, to play both rythym and melody, and even more than one melody at once. The techniques that are learnt from 'fingerstyle' guitar make many techniques unique to electric or 'acoustic' guitars much easier to comprehend and pick up, I think. Also, a classical guitar using fingerstyle technique is better for adaptations from other instruments like piano, in that it can more faithfully replicate the music compared to other guitars.
Everybody learns differently to some degree, and I'm not sure my own experience would be useful to you (I'm entirely self-taught from a family with zero musical ability of any kind, can't remember any piece by heart, and I don't read sheet music and can't 'play by ear'), but if you have any specific questions I can try to answer them. Seemingly, modern guitar education doesn't anymore emphasise rigid styles or techniques or approaches, but encourages the user to develop their own approach, if it works its good. This makes sense, because everybody's hands are slightly different and also shaped by their occupations etc, so there isn't really a one-size approach possible. I wouldn't worry about picking up 'bad technique' so much, you will know its bad if its not letting you transistion fast or smoothly enough between positions, or if it hurts, or if it sounds bad and isn't getting better with practice (beyond just usual muscle development ache or calous development I mean, i.e. fixable by rest).
If you were to go down the nylon-string route, don't get the cheapest possible one as it will dissapoint, but also don't get an expensive one, I'm not sure of price conversion but I would reccomend circa £200-300, and to go to a small/dedicated store and ask because they usually have people working there who play and aren't (usually) trying to con you, so you can ask them and let them know that you have a budget and they, being enthusiasts, will try to help you (though some can be very snobbish, which can be a problem).
In terms of resources, tab books for guitar (even 'classical') can be expensive (but are usually of good quality, more so for 'classical' guitar, and are arranged according to experience - basic, intermediate, advanced etc), and I 'expropriated' some instead, however I will have a look and get back to you because I did also find some sites that had some for free of a reasonable quality (which I've never found for 'rock' or pop music). I will see if any of the book pirate sites have uploaded any too.
In terms of learning, as above, this might not apply to you or be useful as everyone learns differently to a degree, however;
When I was first learning, I dedicated a period of time to just practicing transitioning between chords over and over, sometimes strumming and sometimes plucking up or down (broken chords I mean), to make my fingers learn (like sports), before attempting to play any particular piece. Now, I play particular pieces I'm familiar with to warm up, and then move onto something I'm trying to learn. I don't spend a huge amount of time on one piece, but change to others if I hit a point where I'm not immediately progressing (you solve a lot of problems by sleeping on them, so I don't try overly hard on one particular thing). I started with simple pieces for begginners, but also at the same time tried more advanced ones or parts of them for some time to avoid boredom and too narrow a focus (like with sports, you practice the basics but also try cool stuff at the same time).
Now (though this is a result of previous practice), when approaching a piece I don't know (which with classical pieces is most because I don't really like listening to classical music, except some 'folk' styles of it), I start by not listening, but instead trying to go through the tab as I read it - I don't really understand beats per minute or those kind of things - I kind of infer the general idea from how the tab is laid out. I play it through (once you've practiced enough, you start to be familiar with common 'fingerings' and right-hand sequences), and identify any difficult transitions or unusual positions. Then, I break it up into parts based on that, without trying to improve the difficult parts, but get the easy parts sorted so they flow (again, ignoring for now the correct tempo). Then once that's sorted, I go to the difficult parts, and try to play the whole piece over and over, until the difficult parts are gradually sorted. Then finally, once its all somewhat smooth, I listen to the actual music online and then adjust what I was playing if there are any differences. A lot of the time, I play a piece (even a simple one) slower or faster, even to extremes, than intended, because I find it helps learning.
Playing 'fingerstyle' guitar was a lot more satisfying and rewarding, because you can reproduce melody and rhythm more easily, and I found early on that just strumming chords was a bit underwhealming and fingerstyle on acoustic is not a good way to learn it - picks are used for good reason. But then, having mostly played fingerstyle, when trying acoustic or electric, those mostly don't feel particularly difficult (with some particular styles being the exception). Transcriptions of classic rock into fingerstyle also sound much better imo than those for acoustic guitar, and sometimes than those for electric, since most rock songs have the electric do just a lead line and rely on a bass and rhythm guitar and drums for the rest.
I hope some of this helps, but I might find it easier to answer specific questions, rather than a general one if you see what I mean. Above all, don't worry about being good, or see it competatively, music is cooperative like any human pursuit, even if playing alone - like the whole 'standing on the shoulders of giants' thing you're always playing with the dead in a hopefully not morbid way - maybe its better to say playing alongside our human ancestors. Its a lifelong 'hobby' really, and like anything worthwhile it takes time and practice, but comparing progress to others (especially those in the music 'industry') won't help.
As far as I know, the difference in strings is to produce tendencies towards different sounds, not specifically to make it easier or harder to play, although lighter strings will be easier. I think there are some guitars with super hard strings, because they want a certain sound. Lighter strings are generally better for sustained ringing, and for chords, while heavier strings are louder and also better (with a pick) for melodies because they transmit individual notes better, but can sound worse for chords - they don't ring as long, being heavier. For learning, its all a bit academic, medium is fine, light is fine, very light is also fine, heavy/very heavy will make it harder.
I wouldn't worry about going lighter, unless you want the particular sound (it won't make a huge difference though), but in terms of injuries, if something hurts don't do it, aside from the kind of 'pain' you get from building muscle or callous which is fine, but if it hurts on a tendon or bone level, stop or change your technique.