5yearplan

So I just bought a rust free 91 loyale 5 spd 4wd wagon and have found little bits of information regarding making more power out of the 1.8 and also some snipets of information regarding swaps... My goal is to have a reliable sleeper that can face the toughest northern US winters as well as actually being able to pull in 5th (or even 4th) in 4wd instead of bogging down. So my questions are as follows: how much power can the stock driveline (trans and diff ) take reliably? how much power can be made reliably out of the 1.8? obviuosly turboed ive heard of 8-12 psi being plausible but i cant imagine pistons are stock what is the most popular motor swap to make the cheapest most reliable power ( i know its a long shot) is there any feasible way to make the 4wd be in rwd when it is off instead of fwd? as well as any other info regarding the 4wd system. thanks