Lee,
With your credit you will be looking in the mid to high 7% for interest rate unless you decide to buy down the rate. I do not recommend buying down the rate on a 2 year loan because you probably won't break even. (The money you pay to get a lower rate is more than the money you will save with the lower payment over 2 years).
Regarding the risk of an Interest Only loan and real estate. True, in many areas real estate is suffering at this time. We are seeing a market that is correcting itself after a couple of years of great appreciation. That being said, real estate over the past 10 years nationwide has seen an average rate of appreciation at 7%. Real Estate over the long term is generally a good investment.
I don't think however your focus is long term. Your primary concerns appears to be to get through the next couple of years. That being the case, other than the Neg Am loan (which I do not recommend), the Interest Only is your best option. If you are worried about payinf down principal, add some extra money to your payment when you can. The extra amount will all go towards principal reduction. However, you still have the cushion of the lower payment if you are short money one month.