Hi Lindyloo,
Are you having a reconstruction at the same time or just the mastectomy for now? The recovery will be a little different depending on which one.
Regardless of which, Robyn is spot on - do the physio exercises and take the pain meds. If you get concerned about cording or lymphodema see a physio who specialises in it and they can show you how to manage things early.
Asking how long the drains are in for is like asking how long is a piece of string, you are straight out of chemo so how has your body held up and how quickly can it heal itself? I had left breast done + start of reconstruction 4 weeks post chemo and the drain was in far longer than the right breast which was done 4 months later. The drains aren't gross just annoying, but they are better than getting a seroma and having to have it aspirated for weeks or months - remind yourself it is draining away all the crap. I use to put my drain in a messenger bag and get my friends and family to take me out to fill in my day (no driving while you have drains in).
I needed help with things like hanging out washing and vacuuming for a little bit but was quite able to manage personal hygiene, food prep and light housework - unless you are left handed you may find chopping a little awkward straight up and if anyone offers to help say yes regardless of how you are managing.
It is different to chemo in that you are sore rather than sick and it can be frustrating as you feel better but find it is easy to overdo things. As for side sleeping, again it depends on how quickly your body heals.
I had dissolvable stitches so didn't have to get any removed, different surgeons - different techniques, that may be a question to ask before you go in.
Good luck with it all, Jen