Having H1B & B1 visas together

[yuvapriya]

Hi,
My husband has already got H1-B through a US based company XYZ this September. But he did not join that company so far. Now he has to go to US through his existing Indian company ABC in B1 visa.

1. Will the H1-B be affected if he takes a B1 visa?
2. Can he have both H1-B & B1 together?
3. Without joining the XYZ company if the H1-B is cancelled, can he get H1-B later on (even with any other company)?
4. Can he go to US with the XYZ’s H1-B visa for ABC Company? Is there any formality for that?
5. How can I accompany him if he goes to US in either B1 or H1B visa?

Your reply would be of great help.
Thanks
Priya