Fairy,
Since you are going to McGinn, and I just did, they remove the bag from the catheter when you leave the hospital. So, you are left with a four or five inch tube with a cap on the end of it. You will keep that in until your first follow-up appointment. It stays pretty secure under pads and your underwear. You use those days to "train" your bladder to hold pressure again. It's not pleasant, but it's only about 4 days, so not too bad.
As for moving in bed, you will pretty much be on your back, no side sleeping or anything like that, so no worries about it getting pulled or anything like that.
Kat