Yes.
Yes.
Yes.
Yes.

All based on application of business and regulation as usual - meaning without thought.

RR financial/HR types would drool at the thought of eliminating train crews entirely. However, even the best PTC/automatic train operation systems can't deal intelligently with the clown who stops on the next crossing or the tracks that bend but don't break any circuits. For that you need Mark I Eyeballs in the cab with an appendage that can at least hit the Big Red Button. Also, there are always the odd switching moves that require somebody on the ground - or would you figure all road locos would have remote control gear like switchers and a controller in a closet so the engineer can be the brakeman too - and does such gear have the range to allow somebody to cut out and dispose of a hotbox car a mile or so back in the train, with maybe a TV camera to view what's going on back at the point? For freights, you really do need at least 2 crew; 1 to drive or at least monitor train operation, and 1 to handle the paperwork and jump out when something needs to be done on the ground.

To eliminate crews entirely you have to grade-separate and wall off the entire RR (like BART and a couple of other transit system that use computers to drive), and even then if you haul passengers you'll probably need to keep a "train attendant" (as I think they're called on BART) to keep the customers happy and occasionally hold doors for the person trying to bust through as they're closing. Otherwise, the computers can easily watch what you're doing and make sure nothing truly dumb happens, but they aren't smart enough (yet) to run the whole thing by themselves in the real (i.e. messy, full of wetware) world.