In situations like this, it helps to remember that there is no disjoint between you and the pilots. They are in the same exact situation as you: if the fuel runs out, they crash the same as you. They're not willfully going to put their (and your) lives in danger. They want to get home safely to their families the same as you do.

Dispatch and route planning (and the fuel that goes into the planning) is really intense and takes into account hundreds of factors including stuff like how much fuel do I need if I can't land at my nominated backup airport and have to go to a secondary backup airport.

Domestically, checked baggage can fly even if you don't. It depends on the situation.