Looks like a mistake, it should be +5v.
#1 is ok. This signal would be pronounced "Phase zero", do you have the Greek letter Phi and then the number zero.
Slashed zero is fine, but not really needed since it's unlikely to be confused with a letter O.
Doesn't really matter but "Is there an open" is proper terminology.
Looks like a mistake, I don't see why you would jump back to the point in the troubleshooting.
Looks like they always tried to have everything that goes back to A be joined to a single A node unless it has to cross another line. Sort makes sense since A is start back the start.
I could take a shot that.