Apart from what to ask, it's really helpful if someone not so involved can go with you to write things down. When it's all strange, new and scary, It's easy to forget to ask and even easier to forget the answers!
Immediate questions are when and where, how long you will be in hospital, what to take with you and not take. I had a mastectomy and therefore no radiation (had chemo) and I really had very little pain after surgery. Others on this site can advise better than me about the next stages. Hard as it may be, deal with one problem at a time, otherwise you can get a bit swamped. When surgery is over, and you are feeling you can handle that bit, that's the time to start thinking about your next treatment. And let people help you - you may have been the family fixer, but people can and do step up when needed. As you get your head around treatment, you can pick up again but some free head space now is important. Best wishes for your appointment.