L1B to H1B

[SathyaStaal]

Im here in the US in L1B and the validity in till aug2013

1. I do have a H1B from the same company as L1B - But i dont have the petition # - is there a way to get it through USCiS ? I cant get it from my current employer for sure.

2. If I get a new H1b from a different employer in a month on 2013 H1 Cap :

Immediately (in aug/sep 2012) can I go out of the country (say Canada or Mexico or even to India) for stamping H1b and if it gets rejected - can I come back to the US in L1B ?