The question is how tight does this deal make your finances. 

I rest the cabinet on the board, hold the cabinet tight against the wall, and screw the cabinet in place.

Just as an FYI, I think your numbers --- even with your reduced rehab costs --- is a bit tight.

As of right now the sellers agent told me to hold tight while she gets the deal prepped and ready for the bank approval.

Perhaps $2K or less if the contractor doesn't have to rip open walls or get into any tight spaces.So, if this were my project in a comparable area, this is what I'd budget:- $4K to replace furnace/condenser- $4K to replace all plumbing- $2K to replace all ductwork- Whatever the cost is to fix/replace the damaged sheetrock needed to get to the plumbing/ducts.If the Scope of Work is less, the cost should be as well...

If it isnt tight and sturdy nailing the shingles is tough.

In MN right now the multi-housing market is pretty tight which is good for sellers but to get solid sales prices we would have to rely on local realtors or appraisers in the area. 

., went back to my bank and they might give me a no interest loan for 6 months etc....but timeline might be tight...I am not sure how should I finance this?

We also have two daughters (ages 3 and 8) so money is tight and we haven't been able to save much.

A 1%er in my smaller market here in WA like yours would be tight.