The Cave Columns bug is an ongoing issue. I tried to solve it in the last update and may have made it worse. You're allowed to enter them if you have the Spelunking perk or if you are under the effects of a Wallpass spell/effect. If the latter and the wallpass runs out while you're in a Cave Columns, you'll die on the next turn. It seems easy to fix in my head, but the code there is really tangled. I'll have to spend a lot of time revisiting to figure out how to fix it. I'll let you know if I think I've achieved success.
I like the idea of the merchants stopping if you move adjacent to them... I'll have to communicate it to the player in the manual because it could get a merchant killed if you're banking on the fact it may move out of a monster's way last second, but I think it's a good idea. I'll try to implement that. Also going to implement the auto-center on your character idea. Not sure I have time for any of the above today. We'll have to see!