If you use the stop command and the movie stops, why do movie clips still animate and buttons still work?
The stop command affects only the flow of the main timeline. Symbols on the screen, such as movie clips and buttons, still move and respond at a normal rate.
The nextFrame command goes to the next frame and then stops there. What if I want to go to the next frame and then have the movie continue at its normal animation pace?
You can use the nextFrame command to go to the next frame and then immediately follow it with a play command.
Can I place functions inside button scripts?
No. Functions can be placed only in the main timeline. You can only put on handlers in button scripts.
Can I place buttons on a frame but make them inactive?
Not as easily as you think. You can place a button on a separate key frame and then just not attach a script to it. The button won't do anything, but it will still look active. A better method would be to create a graphic symbol that looks like an inactive version of the button and place it in the same spot where the button would normally appear.