H1 Transfer while it is being extended

[pvm1975]

I am in US and working with Company A. I have applied for Extension through Company A as my petition and I-94 expiring on Mar'08. Now, I have an offer from compnay B and they are not ready to wait for 3 months for the employment. They would like to apply for H1 Transfer right away. I have few questions on this scenario

1. Could my new company B apply for H1 transfer while company A is processing extension
2. Could my new company B apply for H1 transfer and extension at the same time.
3. If my new company B apply in premium processing gets approved and then company A's application get for processing. What would happen ?
4. Could my current company A cancel my petition after knowing the fact that I am switching the employment

Thanks

PVM

Please respond, this is urgent