The reason they recommend the amnio at 35 is that the risks of a complication from the amnio equal the risk of a genetic abnormality at that age, both are ~ 1 in 270 pregnancies. The older the mother gets the higher the genetic risk becomes and it exceeds the risk of problems from the amnio.
I was 35 when I was pregnant with my daughter. I opted for a "genetic ultrasound", it wasn't 3D, but they did a lot more measurements than the regular one. This test is used in conjunction with the Triple Screen and the combination is very accurate for detecting fetal abnormalities.
There is not a test I had where my husband could not be present if we wanted him to, so I'm sure yours can be there. I believe the results from amnio take awhile to come back, but I had my daughter in 2003 and didn't have that test, so I'm going by what I remember my dr saying at the time.
I think you probably have already had some "genetic counseling" and the discussion of the results of your amnio will not feel much different. Your Dr. should have explained the different testing options there are including CVS, triple screen (or quad or penta - whatever they are doing now), and amnio. He or she should have discussed the risks of the tests and the potential for false positives and/or false negatives. When the results of the amnio come in, the dr. will discuss those results in much the same way.
There is NO test where they can rule out every abnormality, they will just say that based on the results of the amnio, that they don't see any markers for X, Y, and Z diseases and that based on these results, your risk of having a baby with one of these diseases has decreased to 1 in xxxxxx. If they were to see a POTENTIAL concern, they would discuss that as well in much the same way, using numbers and statistics, also they would discuss your options for what you would want to do regarding your pregnancy. The doctors will not tell you what to do regarding different tests or treatments, but usually their biases show through.
Good luck! All of our "medical advances" have made pregnancy scary and it shouldn't be. Always trust your instincts and do what feels right to you.