Temple of Moo is obviously a low level dungeon, but there is no key that I've found anywhere apart from the inventory of the hirelings, which seems weird.
Well, i don't remember where i got the keys but by the time i cleared the swamps, i had 3 of them (at least 2 didn't come from hirelings), i think there is one in the cyclops dungeon.
By the way, when i don't know what to do, i check this website, it's the bible for M&M III, IV and V :
http://shrines.rpgclassics.com/pc/mm3/
It's weird you cleared the swamp to be only lvl 10, there's a lot of xp missing, about 5-6 level i would say.
If you're up for it, you could always say REDHOT to a mirror, careful, it's really hot out there, don't wander too far. ;-)
Also, it's really easy to miss some early dungeons, even if checking the world map (there is some maps out there but not in game )
And about the jousters, just you wait to meet the Top Jouster, this one is a mean bastard.
Strange Fellow Russian bots, probably but i was thinking some people might have multi accounts and some other might stick a vote without having played the game but you'll probably tell me people don't do this.