H4& EAD together when H1B extension in-progress

USA H4 Visa
1

Hi,
I’m going to file my H1B extension through Employer and they’ll not file H4 extension.
Have below question.

  1. Now after they file my H1B Extension (Regular processing ) , can i file H4 extension & H4 EAD (NEW based on my approved I-140)together?

  2. If so can i send both I-589 & I-765 together to lockbox of processing center where H1B is filed? This was my interpretation on reading other Post.

  3. How about USCIS fee? Should i do one check for both H4 extension & H4 EAD or 2 checks for each?

Thanks.