I'm sure you would have to be careful how the contract was written to protect both parties.

It's a rental, who cares.

I just hired a escrow company, buyer and me settled on price and terms, and escrow company took care of everything.

Care to share more of that criteria list?

Each time with a small selection of roommates.

You also did not say what your type selection is, makes it kind of difficult to answer what you should do and if you have saved any money for a down payment. 

I deal with the financing/screening/material selection, and he deals with regular maintenance, and anything related to the rehabs.   

A flip is a business, so it is subject to ordinary income tax.The IRS does not care if you buy a house, improve it and resell it or you buy bread, mustard and lunch meat and make sandwiches - to them it is the exact same business model.You can search the vast number of writings I've done on this subject on Bigger Pockets.I agree with your CPA in all aspects and here is why.Running it through an LLC:  If this project comes in at a loss, how is your investor going to prove out their share of a loss or report it? 

Stay focused, learn, and take care of your personal finances!

Select a few investment options that you're interested in.