First good luck to you on this journey. I had a masectomy almost 2 years ago and glad I did. They did a nerve block while I was still asleep that helps pain wise. I didn't have to use heavy drugs for me it was not that painful.
The drain was in for a week and then slowly do the excersize they give you.
I had a big pillow that propped me up in bed and you will need zip up tops if you go with masectomy. I bought on Amazon some zip up hoodies that had pockets inside so you could place drain in pocket. I had an aggressive cancer so chose masectomy over lumpectomy. I use a prosthesis as at 69 did not want alot more surgeries. I have nice cotton ones and a silicone one I got thru Amazon. Thinking of you.

I also did a unilateral mastectomy 2 months ago. I was also offered a nerve blocker prior to surgery. I was shocked of not having the pain I thought I was going to be in. They gave me 10 pain pills and I only took 3, saving the rest in case of pain a few days later but never had to take them. I'm still numb in that area but I had an aggressive tumor so I'm not sure if I'll get all my feeling back. I had the drain for 2 weeks and the bras that have a holding pouch worked perfectly. In my area there is a place that offers mastectomy bras and with my insurance, I get 3 free bras a quarter. They not only provided the mastectomy bras with the zipper but also bras with the padding so I don't look lopsided! Good luck on your journey.