> I'm trying to figure out how to get into level 6 - the only ways I can find are the teleporter/thing in front Kaliti, after which you run into another sign that you can't get past, and the stairs in level 5, which go directly to level 7 (which seems to be the only non-dead-end into level 7). I'm guessing that the object needed to get into level 6 is found somewhere in level 7. I don't think my party can handle level 7 quite yet, but what exactly is IN level 6 that will make it worth backtracking after I get to level 7? Or is there something in level 5 that I missed?

This is a tricky section of the game, because it requires you to, as you say, face level 7 monsters before visiting level 6. The best way to do this is probably to level up a bit on level 5, enough that you can survive one or two encounters on level 7, then do some very cautious exploration.