Get the ice machine the others recommended. Wonderful piece of equipment.
Do the heal pumps all the time. Ask them when you go for your pre-surgery physical therapy session about the exercises you can do in the recliner. Buy a recliner. I slept in mine for 4 or 5 weeks. After the service I am a belly sleeper, and you can't sleep on your belly after the surgery. All that pressure on the knee is painful.
Drink plenty of water, it'll make you get up and walk to go pee. You must walk a little at a time. The knee won't be the problem. Your muscles and tendons will be sore from the surgery and they need the exercise in small doses.
BUY SOMETHING TO KEEP YOU REGULAR!!!!! That first turd after surgery will feel like a softball and be the size of a pea. The pain meds will make it hard as a diamond.

Been a year since my last knee replacement and I feel great. I can do things again. I'm more active. I've lost another 25 pounds too. you can do it. It will change your lifestyle, for the better.