Dredgeworks is crashing when it tries to set up a belt or inserter from [other mod].

Activate "Limit floating belt generation" or "Limit floating inserter generation" respectively. If this doesn't do the trick, something new has gone wrong and you should file an issue report; if a particular belt or inserter is one you'd really like as a floating one and it's not currently compatible, leave a request in discussions.

Are you going to add more tiers of drill?

Not currently planned.

Why is ice generating underneath my crude oil patches?

Space Age. It assumes oil patches on bodies of water are going to have ice under them due to one of the new planets, so it applies that rule to Nauvis as well. It's a little odd, but harmless. These patches shouldn't generate if you also have Cargo Ships installed, though.