I completed the main quest at level 20 or so, the first time... simply I ignored all the other quests, with the only exception of the fighter's guild.
Also, I had quite an easy time, mainly because my first charachter was a warrior, and you cannot stop a warrior armored like a tank and with an unlimited supply of exquisite restore health...
As to the trainers, if you don't mind cheating a bit, here are their locations:
http://m0use.net/~uesp/morrow/hints/mwmastertrain.shtml