If a coin is used the speculating goes down, same reason people don't speculate with dollar value, if X coins buys you a hot dog it gets a lot harder to speculate, the price becomes what people who use it give it. This is similar to gold, while it was used like money it was quite stable, but as people started to use dollars and the dollar decoupled from gold, actual gold became a lot more speculative.

Again no, the more coins people hold the more the value goes up, people actually using the coins doesn't interfere in their price, unless you get to a point where there aren't enough coins for everyone. But even if it got to the point that the price increases because everyone wants to use it and there aren't enough coins for everyone to use, I don't see how that would make mining more expensive. Like I said, processing 1 or 1000 transactions has a similar difficulty. The price of the coin going up could affect profitability, but the amount of ASICS is constant, so the power is already being consumed to mine other coins and would just be pointed here instead of there but would still have been consumed regardless.

I agree inflationary PoS coins, especially ones with smart contract capabilities such as Ethereum are way more useful. I understand the appeal for anonymity, but I disagree on the importance of it, I think most cryptocurrencies are anonymous enough even though like you pointed out they're not fully anonymous.