I wouldn't use a FRAM filter in anything I own...they are very cheaply constructed. They use cardboard end caps that can become saturated with oil and fail, causing unfiltered oil to enter your motor. Buy a filter with at least steel end caps and a silicon anti-drain valve (pay a little more, but whats $4-$8 for piece of mind). There are a couple of good choices out there to be safe. I recommend WIX, AMSOIL, NAPA, Purolator, and K&N. All have steel end caps, silicon valve and use a tight filter pleat. I use WIX in both my Teryx and my quads.
The rear diff is nothing special hydralic/tractor fluid. The only problem I've heard (from customers) is that they are having a hard time find it in less than 1 gallon containers from tractor supply/repair places. Look for something that is compatable with John Deere J20(A,B,C,D) or CAT TO-2...if you need some help PM me I have it in quarts.
The front diff is whatever your putting in the motor. Kawi is SAE40 spec, so anything 40 weight will work, 0W-40, 5W-40, 10W-40
Engine 2.43 qts
Front 0.95 qts
Rear 1.06 qts
Hope this helps you guys out...