Final drive for a 1:1 car is easy. Spur divided by pinion. So if you have an 80 spur and 20 pinion, your final drive is 4.

With a transmission, it's the same but with one more step. Spur divided by pinion times trans ratio. So an 80 divided by 20 is 4 times 2.6 gives a final drive of 10.4.

For rollout, read this or just use a calculator like gearchart.com

http://www.motortuningsecrets.com/rollout.html