I let a mercenary into my party. He doesn't fight or anything and it doesn't give me the option of removing him at the guild hall. His stats are displayed as questions marks. What am I doing wrong here?

OK, so I finally got to level 13 with my Conjurer and my Magician, so I was able to swap them both to Magician and Conjurer. What I DIDN'T know, was that when you switch classes, you start back at Level 1 in that class. So I went to the Catacombs (as I wasn't finished yet), with my Level 1 Conjurer/Magician and level 1 Magician/Conjurer in the back of my party, and they're both, level 6 SORCERERS now, because they leveled up so quickly, because they started back at level one for each class change. Conju...

Found the long staircase on the bottom level of the sewers that goes all the way back to town. However, after exiting that way and fighting past all the ogre lord statues, I can't now re-open the gates to get back down again. Is that it until I get a key of some sort? I have to keep going down through the cellar and sewer levels and the accursed darkness to finish mapping the bottom levels?...

by redline I mean the spoiler free destination list I'm currently in BT2 at Dargoth's Tower as my 3rd dungeon and ... well, I am taking AoE spells that hit for 700~800 damage, my Max Hp in only 300. :<

I've been there from the beginning, though only got to play 1, never got to play 2 or three till now, though always wanted too. My library had a copy of bard's tale 1 in it and was so excited at the chance to play. I even bought 2's strategy guide in antidipation of playing, but my old comodore's sid chip died before I could play it....