bind y doomquest_yes
bind q doomquest_yes
bind n doomquest_no
bind g doomquest_no
Y will respond yes, N will respond no, Q will select a spell, G will cast it.
You must disable the status bar (set the view size to one below maximum) to get rid of the flashing-bookcase issue. I imagine that's the only way LWM ever plays.

The RandomLag error is something Randy added because RL had a major malfunction when it came to being able to use generic images (those not defined as a flat, texture, or TX_ image) on walls or floors. Apparently hquest is attempting to use barback in such a manner, so the error message pops up. It's not something you need to worry about.