Also, what's the recommendation for cash flow percentages?

Also about what percentage of my down payment should I have saved before I seek that person?

@Hong Gao best of luck with the property, I've found that the contractors who don't give written estimates often have some of the highest prices they just throw a ridiculous number out there and some percentage of people just take it. 

Do you know what percentage he was returning on those initial flips by chance?

My partners investment is construction cost, so we need to set raw land value in order to establish ownership percentages.

@Sam Grooms we usually include a certain percentage for construction contingencies for these kinds of situations, but that’s certainly a case by case basis based on the severity of the repairs.

I come across many desperate sellers almost daily but they are still trying to hang onto their property in most cases but a percentage of the masses are open to liquating/selling the property but many are clueless as to how to do so successfully.

As you move up in price point, the percentage of the rent going to these line items will go down. 

Some states don't reassess at all--they just have a starting assessed value and grow it by varying percentages every year (like Arizona and Nevada). 

However, if he is giving you a discounted fee for his labor and is willing to gamble on a percentage of the "profit" instead then that would be okay - but you may have to dig in your pocket to pay that percentage at the back end.