Great looking pilatus!
The "problem" is simply a characteristic of of ANY setup whre the thrust is not inline with the center of drag.
So the thrust can be pointed to reduce the issue or you can simply learn to change trim at different power/speed settings
That's what you have to do on the full size versions.
To answer each qiestion
1
1- flat bottom Clark Y whatever - all the shapes which are NOT symmetrical , simply have a built in angle of attack- you can't fix that - just adjust angle to suit .
2- Not really
3- no- speed will always produce more lift no matter how you angle stuff.
4- no

You have to accept that all airfoils and wing/engine placements are compromises. As are CG placements.

To get good visibility - the wing is above the pilot
To get more power - a long turbine engine made the prop location - way out that.
The big ol clunky looking wing has lots of lift over a broad speed range
The result is a great utilary aircraft

A plane which looks like an EDGE 540 is far easier to trim for minimum variances with speed.
But then - you wouldn't have a Pilatus
would you?