[BonnieR]

I would'nt worry too much about packing. They will probably want you in hospital issue shirts that accomodate IVs, drains etc. and that are easy to change. I bought cute pjs and only got to wear them when I got home. Besides, you dont want to get goop on your nice clothes! Maybe just have easy slippers.
It would be nice if you could get Softee camisoles. They are made for post op and even have pockets for drainage tubes. If there is a prosthetics store near you that sells mastectomy garments, they may have some. else it is mail order. I wore them for a long time after surgery because they are so forgiving and comfortable. find them on line. You dont need to pull them over your head, they can be pulled up.
Yes, stay ahead of the pain. Dont say "it's not too bad yet". That is when you need to catch it. Being in pain affects our recovery time.
Not sure about diet restrictions. Right after surgery you will probably have liquids at first.
Regarding draining tubes, my husband was shown how to master them. He drained them a few times a day and said he just thought in terms of the hydrolic fluid in his car! Whatever works!
Most of your hospital stay you will be groggy and being under observation. you will probably be home before you know it. I was in for less than 24 hrs. But I did not have reconstruction.
Keep the faith. We are all with you.