Didn't Gus get a bit screwed in rotations somewhere due to the hatch
incident? Would he have still be CDR for Apollo 1 if he hadn't blown the
hatch (or had it blow, whichever)

Not really. Grissom had been originally slated for the long duration Gemini
mission (what became Gemini 7) because he had spent such a great deal of time
working at McDonnel on Gemini, Deke Slayton figured he knew the craft very well
and could tought out any problems that may crop up on a 14 day flight.

When Shepard was removed from flight status (and any consideration for
commanding Gemini 3), Grissom was bumped up.

What I find interesting is when discussing the Apollo 1 crew assignments in his
book, Slayton mentions his first choice would have been Al Shepard had he not
been grounded, since he was not an option Grissom recieved the command.

There is an interesting what-if scenario. Shepard moving to Apollo 1 after GT
3...Schirra would probably still first command the cancelled Apollo 205 then
become Shepard's backup. Grissom could have ended up with either with the first
lunar module flight or maybe what became Apollo 8.

Of course there is the fire which would then have claimed Shepard...

-A.L.