L2 to H4 status change and approval questions


I have a query.

Currently I am working for an employer A in L1B and applied H1b from an employer B. But did not apply anything for my wife from L2 to H4 COS.

I have not received the approval yet, but I have a concern. Can I apply my wife H4 by myself after getting the approval or I have to go through the attorney?

Also, from when she can stay here legally; once H4 is applied or once it is aproved as she has a valid I-94?

Because my attorney is charging me not to my employer. Please let me know the procedure if I am applying by myself or missed any document below.

1. My approval petition copy.
2. I-539 COS form
3. Wife's I-94 copy