1) Inexpensive rods have "tip wobble". Not over-powering your cast will help, but it's partially the rod's fault.
However a little wave in the line is a good thing. The extra slack cuts back on "drag".
2) Line control is all about experience. On one hand you're concentrating on your fishing but unconsciously you need to be dealing with your slack line with the other.
I've tried to teach myself to strip in my line and collect my loops from larger to smaller to keep them from tangling,
but I have trouble walking and chewing gum at the same time and this is far more difficult.
Wait 'till a big fish grabs your fly and runs. Then there's line flying everywhere. The only thing that you can do is to form your thumb and finger into an "O" for the line to travel through, hold it away from the reel/reel seat and hope for the best.
Everyone loses a fish this way now and then, so you're not alone.