COS Clarity

[subbu20]

Can anyone help me on the following questions:

1) When I add my husband to my green card process does it make a difference if he is on F1 rather than H4 visa.

2) This is more of a COS question.

Can an employer file for H1B visa while the student has a F1 APPROVAL NOTICE and OPT in hand, but does not have a F1 stamp. (He just has an F1 approval notice - F1 was secured as a process of COS from H4 to F1 while in USA)

Thanks.