When you say it runs at full throttle...... I hope you mean governed RPM, and not open RPM.
If it runs at WOT, did you check to see if the cable is working? That all the linkage is attached? IF the throttle cable is working, and the governor is bad, you would still be able to achieve idle, so I don't understand what's going on. I am guessing that you have a broken throttle cable, or it's bound up.
On the valve thing. It's really simple. The exhaust valve is the valve closest to the exhaust manifold (muffler). The intake valve is the one closest to the intake (carburetor).