Ideally, he would put up the money for the purchase and rehab costs, I’d run the project and then pay him back plus profit after selling it.

Then I would use that lot to build 4 homes as this business undertaking and hope to have the cost of lots be part of my investment, meaning when one day I sell those new homes, I will subtract lots and cost of building from my sales, so to reduce my eventual tax on the profits.

You would recoup your money in a little under 6 years. after that your house is fully paid off, (saving the 75K) and everything after that is profit.

You can do that but every dollar you take in cash or purchase less than what you sell is interpreted by the IRS as taking profit. 

For flipping sometimes it works in high price neighborhoods and the profits are much better with lower risk.

They view them as a taking of profit and it could jeopardize your exchange if audited.  

is the wholesaler is the one who brings the buyer, normally they add their profit on top of the price

I have flipped a property ($60,000 profit) and recently built my own home for $250,000 (appraised at $380,000).

but I like it.. this one the numbers are 160k for the lot bought 6 months ago for cash close when sold probably next 60 days profit about 200k.. net... yes I will have to pay tax .. but so what.

Your market - do you end up more profitable if you charge back utilities with a lower rent, or you paying utilities and bump rent payments up.