Chris,
I didn't run your numbers, but i'll answer some of the other questions.
1) No you don't NEED a realtor, get a purchase agreement signed, take it to a closing agent/lawyer whatever your state has and open escrow. And you're good to go for starting due dilligence.
2) As far as financing goes you have a couple other options you can run the numbers on. First, if you haven't talked to every local bank in your area, you should. If they keep the loan in house, they sometimes will loan a higher amount.
If you make an LLC, you can go to a local bank and put it under a commercial loan. Generally 80-85% LTV (whatever your appraisal comes out to). If your appraisal comes out where you don't have put anything down then awesome. Downside to this is that the interest rates are generally higher and the ammortization is usually 20-25 yr instead of 30. But, you could get out with nothing down. Run the numbers to see which is better short term and long term.
Another option is to bring someone in with the down payment. You can offer them the tax depreciation (payable annually), the principal reduction (payed when you sell or refi), the cashflow, or the appreciation. Or a combination of any of the above.