I didn't find the amnio to be painful at all...but everyone's different. Results take about 1-2 weeks. If you're going to love your child whether they have Down's or not, then I wouldn't do the test. It does carry a risk of miscarriage.
I had that test with same results so I had the Amnio when my doctor perform it I ask her to do the Fish test you will have results in 2 days meaning they will tell you if baby has downs and a week later full Amnio results.
I wouldn't recommend it. You are going to love your baby no matter what. I opted out of it, the risk is not worth it