If not, this should be done to determine if cleanup is required.

BP has various calculators to help determine cash flow and return. 

@Chris HamrickIn your contingency section of your offer to purchase, list a right to get out if you inspect things like plumbing, and the cost ruins the deal for you.A plumber should have no problem testing pipes at certain points to determine leaks or viability of the pipes to be repaired.No Gas should not be an issue.

But first and foremost is for him to protect himself and my opinion is for him to keep collecting the payment and put it in an escrow account to determine at a later date.

If Flood Insurance is still purchased, the client can request a Flood Zone determination to show the building is in a lower zone. 

Perform your due diligence and determine which lender will offer the best terms and be easy to work with throughout the process.

If problems don't shape up, identify in the contract where the pm has not been fulfillig the terms, and determine if you can legally terminate.

When you decide to refinance, is it the appraiser that determines how much the home is worth? 

Whether or not you should buy right now is determined on the deal at hand.

Financing/loans are ignored, your gain is simply determined by your sales price (less actual closing costs) verses your purchase price plus rehab costs (basis).