It's probably a bit much for most tropical freshwater fishes, but some fish like water movement.
Plants don't care if the water is still or moving as long as they aren't blown flat against the substrate they will be fine.
You could put your powerheads on timers and have one at each end of the tank. Then in the morning you could have the timer turn one on for a few hours then it can go off. Later that day the other one (at the opposite end of the tank) could come on for a bit. I would have both power heads turned off at night when the fish are sleeping.
You can have the powerheads facing any direction. Most people have them blowing lengthwise along the tank, others will stick them on the back wall and face them at the front. It doesn't make much difference which way you have them.