There is still a lot of UI and controls that need to be added for co-op.

Both main characters will be able to have a companion or henchmen, that just wasn't implemented in this build.

Currently warriors can do pretty good tossing barrels at opponents (Barrel Crushing Overpowered in Combat?). This build has a bug with physical damage calculations.

The crash with crafting is caused when the result gets stacked with an existing item in your inventory. If you make sure you don't have one of whatever you will be crafting, you should be ok.

Yes, water will make ice or lightning spells more effective.

The music isn't finished, and what was added isn't necessarily playing where it will be in the final game. That said, I didn't notice too much that stood out as not fitting the location.