As a former cyclist (and terrible time trialist), the longest I could ever tolerate on a road bike + aero bars was about 20 miles. Definitely have someone who knows how to fit you set you up right, or you’re going to be setting yourself up for a very very uncomfortable 56 miles of racing (not to mention hundreds of miles of training!).
As for a trainer, I’m on a CycleOps Magnus. It’s an electronic resistance smart trainer with a “wheel-on” design. Super easy to drop the bike into the notches and it’s pretty well good to go. Definitely not the quietest thing on the planet, but it lives in my basement and doesn’t seem to be loud enough to bother anyone upstairs. I really like the smart trainer aspect too, as it allows me to set up a training plan and then it adjusts resistance along the way — keeping me honest and in the correct power training zones. I’ve had it almost 2 years — no problems yet (knock on wood!).