The thing to remember about FHA loans is that only certain housing areas qualify for the program. If you are buying a single family home, there is a much better chance that the home will qualify for the program. Through my experience, if you are buying a condo, not all of the homeowner's associations will allow FHA purchases. I'm not an expert on the topic, just sharing things I have run into in the past. If you can't put 20% down (20% eliminates the mortgage insurance) then it makes sense to go FHA with the 3.5%.
My advice to you on a first time home purchase is buy a home 10-20% below the purchase price that you qualify for. So, if you qualify for a purchase price of $280,000 then look for homes in the $225,000-$250,000 range. Trying to buy a home at or near your qualified amount usually means extra money out of pocket for closing costs and points on the back end of the loan which take the amount you owe above your qualified amount. I hope that makes sense. Also, remember, the fees on your loan are partially dependent on the difference between the rate and APR. A 3.2% rate may seem pretty good, but if the APR is over 4% you're gonna owe some not so nice fees on the back end. Last point is definitely go for the fixed rate loan, even if it is slightly higher than the adjustable rate. Adjustable rates are a terrible idea unless you know you're only going to be in that home for the initial fixed period (usually 3-7 years).
Hope that helps