Alot of running around on the court (I'm assuming you are playing on hard court) will bring harm to your knees no matter what shoe. That said, wearing more stable shoes will definitely help. Those B2 Mids are a good choice especially since you also have ankle problems. I think you would only need the ankle brace if you find that the Mids are still not stable enough which shouldn't be a problem since the high cuts add alot of stability. Adding insoles will also help. I suggest getting a good, heat-moldable one so you can have a more custom fit. Also know what kinda foot shape you have as buying a shoe with the wrong shape could lead to even more pain. Make sure you try the B2 Mids (or any other shoe you decide to get) and make sure it fits comfortably and, especially, has the right amount of arch support. A shoe with too low or too high arches can lead so damage to the foot and knees. The insoles will help with this too but it mostly depends on the shoe.
For insoles, I bought Spenco Total Supports and am liking them. These are available from runningwearhouse.com, a TW affiliate. My Cage 2's had too little arch support and it was hurting my knees, plus I tend to play a grinder-like style when on defense. The insoles helped alot but still feel pain from running around alot.
Lastly, I highly suggest working out the muscles in your legs, especially those AROUND the knee in addition to working the big muscle groups. There's this site with good workouts for strengthening the knees, lemme find it for you.
EDIT: Sorry can't find the specific site I was thinking of but if you google "knee exercises," you should get some good results