Writing this from my hotel room on Wright-Patt, here for my FCI Physical.
To your question about your eye sight, it seems like visual acuity (near and distant vision ie. 20/25) is not the biggest issue, you'll wear any glasses you have while you do many of the tests which won't affect any of your scores and you will still have the same ability to be qualified as the rest of us, this is what they mean by correctable to 20/20, so if you can wear glasses and correct your vision to 20/20 with glasses on these tests, then you're fine. I'm not sure if there is a line they draw at some point with near vision but according to Humey's post it seems like over 20/40 is bad. What really gets people is the little tiny issues with the shape and structure of their inner eye, all of the DQ's I've seen were from weird small issues that there is no way of knowing about ahead of time. Bottom line, there is no way to prepare for/know if you have one of these small auto DQ issues, so try your best not to worry about it.