If I lease my house for one year tomorrow can I then go in and apply for the FHA loan or do I need to wait until it has been rented for one year.

Did you apply closed/open cell spray foam - or strap and use packed cellulose/hemp/fibre - the outer walls and underside of the roof deck (requiring an over roof) or did you maintain ventilation under the roof-deck and insulate over your ceiling?

You may start out managing but if you don't continue then you will not have budgeted for future PM.First you said, "15% Repair & Cap EX COMBINED" then you said "Repairs are being budgeted at $150 a month" so I was unsure of what percentage you ended up doing.I did 10% vacancy, 5% cap ex (which is low), 18% R&M because your last statement was budgeting $150 per month.Our calculations may differ as I take the vacancy from the Gross Rent to achieve my effective potential (some may call it something else) and then begin deducting things like Taxes, Ins, PM fees, utilities (IF they apply).Since you didn't put taxes nor insurance I put $1000 for each.

The "practicing as an attorney" I believe only applies when you are drafting/modifying a contract "for another".  

I live in Oklahoma and not sure what steps need to be taken.Learn the landlord-tenant laws for the jurisdiction where the rental is located and apply them to your business.

If I purchased a 3 flat and I'm living in one of the units of a 3 flat, what's stopping me from moving out in 6 months, renting that unit, and then applying for a mortgage with another lender?

See, the landlord has to apply to the state's attorney general, and they will look at the occupancy.

I'm just about your age too, I started with a Capital One as my first credit card, then opened a Citi Card as well, if they see you paying off your balance in full every month they will gladly increase your limit and you will start getting tons of cards in the mail, don't go too crazy though as applying for too many cards in a short period of time will negatively impact your credit score. 

I don't expect to see any sort of return for several years, but it seems nice that other people will be paying for my property for get better.If I were to finance 100% of it the P&i would be just about 1000 for 15 yearsI'm trying to apply the 50% rule.

As far as the utilities, you can apply a proportional billing based on square footage.