As far as the engine.I've started with a TT 46 Pro.Fast but not too fast with a 9X9.
It flies straight and true and will glide a long way.It want's to stay in the air.Not bad at all.
As far as weak spots the weakest part of the plane is rite in front of the tail feathers at the smallest part of the fuse.This is a very weak location and it don't take much bang for it to crack or break. There's really no way you can reenforce this area until something happens. It will break rite in front of the small former that you can see before you bolt on the tail feathers.My broke clean so I was able to make a neat hole in the top of the fuse where the rods come out and put some glass in there.After the glass cured I put some Gorilla glue on it also and it's doing the job so far.
This is a fun airplane and have put quiet a few flites on it.Handles well and tracks well.
Start with a slower engine and get used to the handling,then go for more speed.That's what I was going to do but have really like the way it flies with the 46 and haven't changed it.

Good luck
Walt