According to BM representatives they start shipping very small quantities for preorders in the last week of July 2012.
Most probably, enough cameras will be available only in August or September. May be even October.
It could shift further forward, but I hope it won't happen.
So, do not plan that you could start shooting in August. Be safe and assume that you'll have it in October or November.
If you need camera earlear, buy another camera.
Most certainly yes. I think shortages will maintain for three, may be four months. You must also take into account that if some early bugs (with sensor, battery, overheating) will be found during initial batches it could shift the date then it'll be available in your store for another few months.