what sample rate and bit depth do you receive files and export at?
Depends on the project - the 1975 album is 48k 32-bit which is typically what I go for if starting a new session from scratch
Any reason why you use 32 over 24 bit?
The main reason to use 32 bit is if committing busses that are clipping internally. Sometimes you’re in a flow with a producer or artist and you don’t want to have to worry about gain staging as much. So it’s a nice safety net and one less thing to worry about! Same goes if you want to bounce elements together and the output bus is clipping at that moment.
Pro Tools always uses a 32 bit float mixing engine regardless on bit depth of audio files. It believe it also makes all committed tracks 32bit files by default even in a 24 bit session, but if you then did a save copy in of these files to another 24 bit session they’d then get clipped (and sound clipped/terrible).