With Dragonborn in my underground cell 3 Betty netches consistantly are spawned near my entrance. They float above the ceiling with their tentacles dangling down. They can be killed and when they are their bodies drop through the roof to my floor. This happens even when I coc from a new game. Once I also got a mammoth in my basemant. Removing Dragonborn fixes the problem.

Any suggestions about how to fix this? I would like to play this DLC but not with large wildlife appearing in my home.

I also get combat music and netch noises but no visible netches in my Lokir's Tomb I created in the tutorial.

You might consider removing the creature spawns from the cell if you built it in CK.
The music, if any, is settable in the cell properties menu.

Netches are huge and really do not go with most interior cells.

This should be in the CK modding area.