In GA/SC, I've seen PM's take this on and they don't charge a %, but a flat fee to transfer service when a tenant moves in.

Let's say my appreciation is negligible and I'm basically flat - the economy hits the skids and I'm up for my first five years or so and then down for 5 years and I'm selling into a recession so my appreciation is nil.

One I believe it was Datsun ( that's what Nissans were called in the early days for you younger folks out there) they were the first auto manufacotrer to offer 0% financing.. which of course as we know has been copied for years and years since the mid to early 80s.Second was I had Saudi clients from San Francisco that because of religious reasons could not pay interest So since we owned all the properties we sold.. ( my dad was in the land business big time 300 to 500 sales a year)WE came up with our own 0% financing and just flat killed it.. 

If I'm able, I'll build a granny flat to live in while I rent the house on airbnb.

Well, it may be free for you now, but when one of those panels shatter it's going to be $200 in materials minimum to replace the whole door quickly, and you'll have to change it quickly and pay a premium for that as well.

They might  just charge a percentage, see if you can find one with a flat fee - You will definitely want to do a title search / get title insurance to verify what liens have been put against the property.

Expensive things to look out for: foundation issues, termites, plumbing supply and drain to the street, outdated electric panel (60 amp fuses) and shake shingle roof in bad condition. 

This is a great first project for me since I'm starting with close to no capital and will need to maximize profits as much as possible.So far, all the carpet and flooring has been removed, kitchen remodel has begun, we've gotten two quotes on HVAC (the home has central heating and ducting already installed, just needs a unit), and yesterday we had our drywall guy scrape the popcorn ceilings and add a texture (which is much cheaper than floating all the ceilings flat). 

I had a landlord with a similar problem; he ended up averaging out the water usage based on the number of units and charging a flat rate.

How are the sightlines from the street (flat, raised, in a hole view)?