H1 approved for Company A want to join Company B

[neeti865]

Hi,

My H1b (first time) got approved recently for year 2015-16 with company A and I have I797 approval notice (original) with me which is valid until 2018. I haven't got my visa stamped yet and I am currently in India.

I am planning to apply for company B and would want to work and travel through it. Now, my questions are:

1. What are the exact documents required if company B wants to apply my visa under cap exemption category?
2. Does it create any complication while company B is filling my H1b petition? As I've never traveled/work on my original company A.
3. If I traveled with Company A, after getting my visa stamped, later, when apply for H1 transfer, is it a hard requirement to have 2 months salary slip?

Thanks in advance for reply! I'll appreciate as I need this information urgently.

Thanks Neeti!