Once you subtract the other expenses I'm ignoring, you may find no profit in selling. 

If something were to happen and you put in a claim, (only do so if you REALLY need to) the 2500 would just be subtracted from the payout.

The value will be less as a duplex and subtract the income of the removed 2 units, then reassess the value of the property and propose the lower purchase price to the seller.

Thats based on the $775 in expenses subtracted from $900 per month in rent equals $125 in monthly cashflow (before vacancies).

Here's how you figure that...take your monthly gross income and divide by 2.Next add up all your monthly credit payments ie car, credit cards, student loans (unless deferred), medical bills etc.and subtract that from half your gross monthly income.

But with real estate you don't just settle on a purchase (Wholesale) price of 65%- you need to subtract your repair costs, holding/closing costs, and finally YOUR profit you want to make- usually $5-10k in Detroit.

If you arrived at your initial offer on a per square foot basis then I think you should subtract $30k from your offer price, at least as a jumping off point.

Do not subtract any lender related/required costs (if any) and any operating items such as prorated property taxes, prorated rents, HOA fees, etc. 

What would folks add/subtract from this list?

I would think the value add/subtract of a fireplace would be negligible to an investor.