Adjusting the throttle and clutch cables is just like adjusting bike brakes. You can adjust at either end of the cable with the screw that the cable feeds through.
If you need to adjust the clutch itself, there is a thread somewhere in Classic Instructions for Building and Repairing Motorized Bicycle Engine Kits - Bicycle Engine Kit Classic Posts at Motorized Bicycle Forum
that has what you need.
For starting/choke operation, here are my best results:
I don't ride the bike to start the motor. I pick up the back seat and with the clutch released and the other hand on the throttle, spin the pedals with your foot (helps to be in a fairly low gear - I use 2 on the front, 1 on the back).
So when starting first thing in the morning or after it's been a while since riding, I put the choke FULLY on (all the way up) and crank it over once. The bike won't start, and will barely sound like it's trying. Then I put the choke at 1/3 to 1/2 on and kick it over again, twisting the throttle. It'll start right up usually. Pull in the clutch and lock, set the bike down, and let it warm up for a couple minutes. I start my bike like this every morning and it always starts right up. This is also the easiest way I've found to start weedeaters and leaf blowers