1) Yes. You are a mesomorph body type and thats what they're made for.
2) Might as well just mod the anovos gaskets anyways, you're already getting them with the armor. Do what you feel will be best for your approval level goal
3) Imperialboots is quite well known and you'll probably be fine with ordering your size. They're professionals, but check their website extensively first, maybe even email them.
4) The standard line lenses should be fine. Echo's can be avoided if you place your mic and fans away from each other or if you have padding to soak up the sound. Fans, mic, audio box.
5) Check ukswrath's thread http://www.whitearmor.net/forum/topic/34011-ukswraths-first-order-heavy-gunner-flyye-vest-modification/
Hope this helped!