I think you already know that your weight is the majority of your issues, including your knee.
Absolutely ask the plastic surgeon about which should come first, but, I would say the weight should. As has been stated, after you lose the weight you may have skin to be tucked and removed, and it will give you the best possibility for the breast results you want.
I have not had a reduction, but have had some elective plastic surgery done, the last was in January. Breast Augmentation was one. I believe that the recovery from the augmentation is more difficult than reduction because of the prosthesis going under the chest wall.(muscle) and I do not remember that being horrible. You are sore for a few days, but you have to get moving.
US news just came out with a new "Top Doctors" list that is one that is not partial and more objective than most lists. You might look there and see if there are any surgeons near you on that. They represent about the top 3% of surgeons. (Mine just made the list
Make sure you understand where the incisions will be-I have no idea about reduction, but the best for augmentation is around the areola, as opposed to under the breast. Heels better and nerve function returns within about 6 months.
I would also make sure that your insurance will cover this because of size and issues it has caused-otherwise it can be very expensive.
As far as hospital stay-I doubt you will stay over. Most plastic surgeries are done as outpatients. My surgery in January was a 10 hour procedure (UGH!)and I went home (well to my surgeons house, but most go to their own) after.
Many people do it....it is well worth it.