If you want to keep up with daily events in the Executive, the Federal Register (Fed. Reg. or FR) cannot be beat. It contains all of the FOIA request, every public inspection requirement, CFR proposals, Executive Orders, Presidential Proclamations, and so forth.

If you want something more specific to rule making, you can find that here. Rule making makes a bit more sense when you think about it. Say Congress passes a law that says "build me a road between Texas and South Dakota". The law will usually say who (department) is in charge of that and then that department will take the money and begin rule making. Rule making is basically laying out the path the road will take, what kind of materials will be used, what companies are allowed to bid, environmental guidelines, etc, etc ,etc... Once those rules have been made the who is going to do it is determined. Like Highways in this case, the Federal Government provides the money and the States are the ones who select the labor and make minor course corrections to the highway (like if it's about to pass through a cemetery or something).

Rule making is also sometimes called regulation. Because the agency put in charge is regulating the action being done to ensure compliance with what they think the law is asking for, because Congress is very NOT detail oriented until they really want to be. Also with rule making, Congress can "ask" a department to come in and meet with them if Congress thinks some of the rules don't mesh with what they were thinking.

There's also override laws, which Congress passes like a normal law. These laws, remember the Constitution requires laws to be applied equally if they involve the public so these override laws are written as such so that they only apply to a executive department, specifically smack the department over the head and "corrects" where the rule making went wrong. These don't happen often, but we did have one back in Trump days over the FCC. The FCC had made a new rule that required ISPs to get permission to sell customer data, and Congress plus then President Trump overrode the FCC, explicitly banning them from ever creating such a rule. It's still open if the FTC could make such a rule. But that's an example of an override of regulation.

Oh also my whole comment didn't even touch on the Federal Vacancies Reform Act of 1998, which is what would happen if a Secretary quits. Very, very, very long story short. The Deputy Secretary automatically gets to become the "acting" Secretary BUT they cannot do any "exclusive actions", which that Leahy rule is indeed an exclusive action. The "acting" Secretary can only maintain "status quo" until the Senate Confirms that the acting secretary is indeed the actual secretary. But an "acting" position can only last for 210 days, after which the office is then considered "vacant", but none of that matters anymore because Congress uses "pro forma" sessions to prevent recessed appointments. But typically, if a position is "vacant" and Congress is not in Session, the President can make a recess appointment.

If you ask me, what we really need is an Amendment to the Constitution that provides the President a way to declare Congress as absent and if some threshold of Congress doesn't become present, then the President can then call Congress not in Session. The whole "pro forma" sessions of Congress really needs to stop, like in a really bad way. Sort of like how Filibuster should return to requiring a person physically speak for the entire duration of the filibuster and must remain on topic.

Congress has gotten really soft on everything and that's allowed them to permit a lot of bad faith actions in Congress to happen. It used to be that it was "gentleman's agreement" that Congress would behave and act in good faith, but boy have we really fallen down on that since the 1980s.

Anyway, I'm rambling.