Dear ang3
It's been 13 years so my memory is a bit vague, but I didn't do much. Your experience will depend on a number of things - the size of your wound (I had lymph nodes removed too), your healing rate, drains, any muscular aches or twinges. I was encouraged to shower while in hospital - I had no problem with the wound (waterproof tape) but the drains were a pain in the neck. When clothed, I put them in my dressing gown pocket in hospital but in the shower they were on the floor and easy to trip over. With any luck, you may not have to go home with them (I didn't have to), but if you do that's one thing to be very careful with. I'm mainly a right side sleeper too and I did not have any problem.
In spite of losing 17 lymph nodes, I had excellent arm mobility from the start. So no problem in using my arm for most normal activity. You may however be told to limit your use to begin with, to help healing, which may mean some help for some tasks (hanging out washing, for one). It's pretty normal to get some twinges as you heal, and after. Scar tissue can occasionally cause mild discomfort, for longer than you might imagine - stretching is usually the best remedy, once your wound has completely healed.
Discouraging pets from your bed is a hard one - but it's unlikely their presence will cause any problems as long as they are not actually in contact with the wound! Normal hand washing after pet handling should be sufficient, I certainly wasn't warned about anything.
Bes wishes for your treatment and a rapid recovery.