1)if both B and C are approved with I-94, “Last Action Rule”applied.
-No “Last Action Rule” applys to the same status applications. No matter which H1 petition is approved earlier or later than another, your status will be H1. You can work for any one of them in tis case, up to you. You only work immediately when the H1 approval has I-94, if no I-94, you need to go out of US to get the H1 visa to come back. The following questions have the same principle as this one, so I do not answer them.
2)if B approved first with I-94, but C approved later without I-94, which one is valid? Can I go to company B? Or I have to take C and go outside of USA for visa?
3)if B approved first without I-94, but C approved later with I-94, Can I go to company C?
4)if both B and C approved without I-9, I can take any of them to stamp the visa outside? right?
In addition, when the company C file my H1B, it is based on company A since no approval from comany B. Is that OK?
Thanks!