I guess I'd only ask three questions of someone who has never been on a trip:

When you see something that needs to be done, do you tend to step up and do it, or wait for someone else to take care of it?

Do you complain about the weather, or do you buy the right clothing to deal with it?

Do you enjoy the feeling of total and complete exhaustion? (hmm . . . maybe this is the only one I would need to ask)

I figure the rest would take care of itself.  Granted, I've never tripped with somone I do not know well.