THe best idea for a rental property is to buy one thats a REO or dump, build it up to your specifications TILE EVERYTHING, and idiot proof the house versus buying something turn key. 

My long term goal is to collect residential rental properties without the intention of reselling them (not yet, at least).

Fits you perfectly bro.Buy your first house as an owner occupied FHA Multi Family (3.5% Down) collect rents, live there for a year, get used to being a landlord and the responsibilities involved...after 1 year go buy a nice single family home with a Fannie Mae Loan - 5% Down and rent out the unit you moved out of in the multi.

Evictions can take a while, and damage needs to be fixed, and then some kind of marketing for a new tenant  I recommend three months reserves for every property  I recommend that you be licensed so that you can show the property in case it interferes with your realtor laws in Oklahoma  I also recommend that you have some kind of a collection company that takes the payment directly from the tenant buyer to the mortgage company not to the seller  If you do have reserves, and the tenant buyer wants to buy the property, I use a reverse assignment technique that basically create your equity in the contract in the form of a note, attached to the property, and instead of two closings you have one closing, a new contract from the seller to the tenant buyer, but you get paid when the house closes and pays off your noteI love Oklahoma City because it has great  Yeilds between what you get from rent and what your mortgage payment is PITI

It's kind of like a really nice private man camp I guess.He is currently collecting about $5,500 in rent at 100% occupancy and covering all bills for the tenants.

That would involve either showing proof of funds or talking to one of my preferred hard money lenders to get pre-qualified based on income and assets.  

I am currently renting a place for $1,000, and I would like to "house-hack" and live in the 1BR unit (all numbers assume I am collecting rent from all three units though):Offer Price: $365,0003% Seller Assist: $6,400Total Income: $3,200Unit 1 Rent (2 BR, 1 BA): $1,250Unit 2 Rent (2 BR, 1 BA): $1,150Unit 3 Rent: (1 BR, 1 BA): $1,100Total Monthly Rent (before vacancy): $3,500Total Monthly Rent (assuming 1/12 months is vacant): $3,200Total Mortgage: $1,940Monthly Mortgage: $1,700MIP: $240Total Expenses: $1,065Maintenance/Repairs: $280/month (~8% of total monthly rent)Property Taxes: $240/monthInsurance: $170/monthCapEx: $175/month (~5% of total monthly rent)Water: $150/month (not metered)Miscellaneous: $50/monthFYI - did not budget for property management, because I intend on living here long-term and self-managing$3,200 - $1,940 = $1,260$1,260 - $1,065 = $195 cashflow/month

Not only will most sellers require that your financing/proof of funds be in order first before entertaining any sort of offer, but you also want to know how much home you can afford based on your income.

Then collect a security deposit first and last months rent then you have no interest and the same money up front.

The current owner built the second home in 2009 and has proof of inspection and permits from the city for everything.