I talk myself around the track as well. Remind yourself to stay loose on the bike, relax the death grip, keep it smooth, encourage yourself to chase the guy in front etc. I've had a suprising amount of holeshots after a big 'C'MON' as the 5 second board goes sideways..
I think you'd be surprised how many people talk to themselves under their helmet.
I remember asking a particularly fast junior why he whips his bike sideways at every possible opportunity, he just told me it helps him relax & makes him feel like he's the best rider out there. Whatever floats your boat man!
The breathing thing comes from nerves too. Race more. Just race anything you can enter. Doesn't matter if you have no chance of winning, it's all about the act of going to the start, the gate dropping and actually racing. Racing will become more like just riding, and you'll just get into it. Plus, you'll get fitter doing 7 or so races in one day..