H1B with approved I 140 --> H4 EAD --> I45 EAD

[True Indian American]

Dear Experts, 

Please review our situation and advice to the below questions. Many thanks in advance.

My case: 
approved EB2 I140 - June 2016
Current H1b- petition approved till Dec 2022

My Fiancée: 
approved EB2 I140 - Sep 2019
Current H1B - petition approved till July 2023

Question: 
1. Is premium processing for H4, H4EAD available?
2. Pros and cons if I move to H4 EAD based on my partner’s approved I 140?
3. Let’s say in near future the filing date for EB2/EB3 move to July 2016, will my employer be able to file for I485, EAD, AP without moving me back to H1B from H4 EAD?
4. Is it advisable to downgrade to EB3 now considering EB3 filing dates have progressed to Jan 2015?
5. For I485 EAD and AP extensions- can I independently file for future extensions or my employer would need to do it?
6. If I use H4 EAD now, will there be any issue during my I 485 EAD?
7. What are the fees and timelines for H4, H4 EAD, I 485 , EAD and AP along with PP?
8. pros and cons of moving to H4 EAD vs H1B?
9. Pros and cons of I 485 ( EAD and AP) vs H1B/H4 EAD?

Edited October 2, 2020 by True Indian American