I don't have the stomach to just raise the rent $600 in 1 year.

While it seems like a quick way to fund projects, I do not understand how the loans can be paid off unless you are strictly flipping the house. 

Plan to raise to $13504th house (corner lot)-$175k 2/1.

I am currently looking at a property, still the early stages and may not work out, but it raised a good question.

One way is to see if a Hard Money lender would fund 75%-90% of the purchase and 100% of the rehab.

For example, doing a 30/70 equity split where $100K is needed to be raised between 3 LPs, one invests $50k and the other two invest $25k, would the $50k investor "own" exactly half of the 70% LP equity and the other two investors would "own" 25% each? 

The escrow and title company are the ones disbursing the funds, so you just need to bring cash to closing.

i.e. proof of funds, pre-approval letter, signed disclosures, etc- What experience do you have working with house-flippers, and other investors?

Lots of issues to consider like title insurance, due on sale, comingling of funds, IRS red flags etc. 

If you were raising money from investors then maybe consider a corporation but if its just you, LLC should suffice.