- #1
When do i use "drive" or "driving"? 
- #2
So you are effectively asking about the difference between these two:
1. She stood there and watched him drive away.
2. She stood there and watched him driving away.
1. tells us that she watched the action completed; 2. that she watched it as it was happening.
In practice they are fairly similar, but the emphasis in 1. is on the completed action, and in 2. on the action as it was happening.
- #3
Thanks Tompion for your help.