RE: how much wind is generally too much?
The topography makes the difference. Have hills and buildings around ? Then expect eddies and turbulence in almost any wind. Live where its flat and there are no obstacles for miles, then it might be smoothas silk , (laminar,) when blowing 30kts.
The type airfoil makes a big difference. Flat bottom airfoils are used on trainers because they allow the airplane to fly slower which gives the student more time to react. But flat bottm airfoils are very sensitive to turbulence.
Symmetrical or semi-symmetrical airfoils handle wind much better. ( buth make for a faster airplane which isn't what the student pilot needs)
The aspect ratio effects performance in the wind. Is the wing long and skinny or short and broad ? Low aspect ratio wings generally perform better in turbulence.