Hey Mandi,
The Catheter is your doctor's preference - but most do not use in a short procedure such as this. I did not have to have one for my LB - it is not too bad - I have had one for other procedures.
Most doctors allow you to shower and wash gently over your incisions 24 hours after your operation.
As far as the pain meds go it just depends on your doctors usual manner of doing things. In my office I had one that gave before hand, one that gave as part of his discharge and one that did some of both. Many do give before. You might call and ask.
GOOD LUCK!