Does my Husband need I797 form for H4 visa ?

I am on my H1b visa and I want to apply for my husbands H4. So my husband contacted the agent over in India and agent gave him below list of documents he needed.

1- I797 Wife

2- I797 Husband

3- job letter

4- pay slip (2)

5- bank statement last 3 month old

6- passport copy of all pages

7-sponsorship letter

8-invitation letter


1) How I will get I 797 form for my Husband ? Is there such form ?

2) Do he really need a sponsor letter ?

3) Why would he need invitation letter ? I am not inviting him for any occation. I am calling him so that we can stay together.

We are so confused. I would really appreciate your reply.