RE: covering 4*40
Don't wory take your time and it will be good.
It was my first covering and learned a lot.
For decals use windex method, which is simply sparying windex on the covering than putting the decal and removing air bubbles with piece of plastic/card.
also make 45 degree cuts at the corners ro avoid 90 degree angles, I leraned this from MinnFlyer and works great.
I went over the edges with trim solvent to keep them down.
Webra 50, will be good. I have unlimeted vertical with 46FX and 11x5 APC.
Enjoy it.