A drive will not be erased when disconnected.
Steam is pretty good at dealing with first run installs for games. This means it will deal with installing required runtimes(you need these to play the game).
For steam I do not see a reason for it not work work.
I normally have steam on the system drive and games on another when the system drive runs out of space, but it should work. Either way, files are not removed from disconnected drives.