The "hardest" part is the daily action steps and commitment of time/effort to get it moving.https://store.biggerpockets.com/collections/all-books/products/finding-and-funding-great-deals Finding and Funding Great Deals by Anson Younghttps://www.amazon.com/gp/product/1259643883 Building Wealth One House at a Time by John SchaubIf you need anything, don't hesitate to reach out.

How do I get or create a proof of funds letter for the seller?

How is it you intend on collecting from this person? 

The question I see, is if their policy covers it (when you get proof of insurance from their agent ask that question) and will the Building inspector sign off on the work. 

There's nothing wrong with rent stabilized properties, as long as you're collecting the anticipated/expected rent.

He collects the data and sends it out to hundreds of different lenders.

Now we rent our old unit and collect good cashflow from the property.

We collect first, last, and a security deposit equal to one month's rent when we turn over the keys.

Generally the seller and buyer sign a form acknowledging the procedure and agreeing any difference between what was collected and what is owed will be settled between then and is not the responsibility of the settlement agent.

I assume there’s a government department in charge of collecting these fees, why else would they require licensing.