once my plants are done stretching should I move t...

Depending on your plant I'd say 100% power at 18 inches. Watch your pups and see how they react, you may have to raise it higher or lower depending on how your pups respond gooe that helps.

I'd say at least 18-24 , 100% power and watch your plants they will tell you how they like it. Then if you have to adjust accordingly.

I don't understand the need to do that... the buds themselves will continue to grow and bulk up and out... I usually have the problem of the lights being too close! You don't want to burn your buds... Good luck!

If they are dimmed down, just turn the intensity up as they flower. If you don't have a dimmer, or they're on full blast, i don't see any harm in dropping the distance. Just make sure you keep an eye out for light stress.