Do me a favor and double check the Krebs safety, make sure you put it all the way through. Some make the mistake of not putting it in properly, all the way. Seems pretty odd it doesn't fit your WASR, it should slide right in just fine. As for it being 'too stiff' this is a normal/good thing, you can always bend it a bit to make it more 'buttery smooth' as you need (hell just like you can with the 'factory' safeties).
As for the muzzle brake, 14x1 left-hand threads are what standard AKM rifles use (probably what your WASR takes). I'm guessing you went with some 1/2-28 (AR-15 type) threaded brake...
When I say 'standard' that really means the AKM (Type 4) pattern AKs out there, this is by no means the be all for every AK. I have 24x1.5mm right-hand threads on my AK, which is of the AK-100 pattern or style.