I am a candidate for knee replacements and have said I will not have them done until they find a better way to do them. If you have followed hip replacement improvements the past few years, they are now done with a very small incision and many people go home on day 2 and are back to their normal activities. Surely there are better methods of doing the knees. Find out all you can about the surgeon and what methods he uses...also which devices give the best service to the patient. We need to be our own advocate for any surgery. I needed disk surgery and interviewed 4 doctors before I found one who met my needs. He did 2 surgeries for me (4 years apart) and I had excellent results. Don't settle for a surgeon until you are absolutely certain this Dr. can do the job for you. I think that having both knees done at one time makes a lot of sense. Why go through 2 surgeries.
Lots of good information is available on the web but "word of mouth" from experienced people is also of great value. You are wise to ask for helpful information from the people on this board.
Then learn what you need to do to prepare yourself for the surgery. Exercise to increase the strength of the quadricep muscles that support the knees is very important.
I wish you well in this adventure.