[X] Ask them if they'd take a look at the treasure map for you. You're kind of curious to work out the exact what and why of how it works, and who better to tell you than a (quasi) expert?
[X] Ask about the damn gold already, you've put it off too long and you're starting to get the shakes. The map pointed you to treasure and you won't leave empty-handed.
[X] Ask about the weird black water, if it's 'not' water and they've been experimenting on it. Does it have anything to do with the capped well you saw outside?
[X] Ask about the tower's owner. What were they like, what was their deal, where did they go, what did they intended to do, etc etc. Boring small-talk stuff you don't care about.