Re: 106 Questions

#2
You might find this an answer for the first question (he's not mindless, but...)

Regarding the other two, no canon info about those things, so any answer you see will be personal opinions. My own is that his "acid" doesn't harm him, and that he passes through walls by entering and leaving his pocket dimension, from where he can presumably see the full size of the room he wants to go and stuff.
Creator of SCP-345, SCP-700, SCP-860 and SCP-966.