When I started I did 96's, now I just do 72's. Nowadays I treat my fast like it's a religion. I lost 100lbs in about 6 months with a couple screw ups here and there. Then I took some time off from fasting for a few months and gained some weight back so I hopped back on the fasting routine. No plans on turning back ever again for me.
Treadmills can be really hard on your knees and hips if your body isn't used to moving quickly at a high weight. If you have access to a pool or a body of water I recommend swimming as probably the best low impact cardio when you are heavy. Elliptical's are also great for a lower impact workout. I bought a stationary bike when I hit 300lbs as my reward and have been obsessed with it since. I can spend a few hours on the bike and just watch a show or listen to a book/music.
The biggest thing is consistency. Pick a routine and stick with it. Don't waiver. Ever. You got this!