The problem of line landing in a pile is the result having an arch to you casting stroke.
You want the rod tip to travel an the same flat plane.
As for snapping flies off you just need to pause at the end of the stroke before reversing direction to let the line straighten out so you don't crack the whip and loose flies.
Overpowering on the forecast is not your problem. That error would result in tailing loops not with your line landing in a pile.