I have a solid deal with a private investor supplying the cash for down payment.The cashflow is around 8.5% Cash on cash.How much money should I be giving him for his 100,000 promissary note / investment ?

You should know that laws and regulations change from state to state and obviously from one country to another when it comes to real estate investing.

auction.com website hosting bank owned, there seems more possibility to do hard money.as a rule if you're dealing with a county's auction directly even hosted by aucton.com that defaults to county, I would not use a lender (hard money company) regulated  by the state or national level) and i dont think they can fulfill a county auction closing timeline and you lose your deposit.

Other than just paying attention to the zoning regulations, Is anyone aware of a tool that will help identify the percentage of each in a given area?

@Daniel Mendez I tend to focus on outlying markets, they have cheaper land cost and better zoning regulations for building high density affordable housing. 

You want to make sure there are no issues with city or county regulations.

If you don't have an existing network that supplies you with new deals, you can go to any of the crowdfunding sites such as Crowd Street, Real Crowd etc. and/or you can join an investor club.If you're conservative, then it takes a lot more work to locate the few that you might find suitable.

Marketwise, you want to look at not only growth, but also supply constraint.

What are cities that have favorable regulations for Airbnb and a good market since I don’t have to operate in Philadelphia? 

the rent regulations in the city are making it impossible for landlords to make money, especially the smaller landlords. are you looking at a multifamily 6+ units?