I understand you have already ported, that is just fine. You were never required to notify USCIS of porting.
1. Should i go ahead and file for AC21 along with my RFE response?
You don't "file for AC21". You merely notify USCIS you are using that law.
Yes, you send that notice letter with your RFE response just as I said above.
2. If so what documents do i have to send to notify AC21 in addition to the AC21 letter that you mentioned?
I told you that you need a letter from your employer in my first response.
it has to set out the date your employment began.
The salary you are being paid.
The job duties in great detail. The job details should the the same or similar job description that was in your PERM and the I-140 petition, but no reference has to be made to the immigration documents.
If you have these send them:
1. Copy of LC approval
2. Copy of I140 Approval
3. Copy of I485 receipt
4. Employment Offer/Support letter from companyB
5. Copy of the employment authorization
3. RFE requests forms I-766 but all i have is EAD cards. Should the front and back copy of this card suffice?
Yes, the EAD card is the I-766
4. RFE requests I-797 approval notices showing i was granted status in a employment authorized non immigrant classifciation. Does this refer to H1B approval notice?
Yes, they are asking for the H1B approval notices
5. Also I was working for company A with H1B status and transferred my H1 to complay B who applied for my Green Card application. Do i need to send the approval notice from company A as well since the RFE mentions all documents from the date i filed my I-485 to present?
You send them exactly what they are askinng for - approval notices that cover the date you filed your I-485.