I didn't read the whole post, but if it wasn't mentioned, I found a good way to take action shots with an I phone. I record all my riding by placing my phone on a log or some sort of stand. I then go back and take snapshots of my videos, never missing the the perfect shot.
Get a decent smartphone, use phone to access B & H Used Camera Departmernt, buy any digital Canon or Nikon SLR body only and a f1.8 prime lens for the front. Boom.