Much of the negotiations during due dilligence depend on demand for that specific property- hopefully your agent has build leverage in to your contract that they can use to help you with this piece. 

Now, it took me many years and a lot of real estate trading to get to this place with my bank, but that is why I highly recommend that RE investors work hard and finding and nurturing a local banking relationship.

Cost will likely be around $120 - $160 / sqft depending on finish out and how much one the existing house needs to change.

It all depends on your investor profile.

As far as I know, Catskill doesn't have any real regulations on them.

For me I think it depends on how much money you have invested into the home and for how long?  

Based out of Salt Lake City and looking to do multi-state investments in real estate by flipping or renting. 

Depending on what your investing goals are you want to looking into self directed IRA vs. checkbook IRA or even better if you qualify Solo 401k.

Depending on the area, it might not be worth adding the rehab.

It depends on what you want to invest in.