H1B ammendment with extention

USA H1B Visa
1

I have a approved i797 till Jun2019 and my client is A at location AA. I had a transfer in Aug 2018 to client B at location BB. My company filed extension plus ammendment for me (normal processing) in Aug 2018. They requested the duration till Aug2019 in the petition. The decision is not yet done but i need to file for extension as the i797 is the expiring. As I understand i would need to file another ammendment plus extention if the prev petetion is still in progress. My question is

  1. Can i file the new one in premium?
  2. Is it better to file both in normal and wait for it or should i upgrade the current petition to prem and then apply or put the new one in prem?
2

  1. Can i file the new one in premium?
    Ans: Yes

  2. Is it better to file both in normal and wait for it or should i upgrade the current petition to prem and then apply or put the new one in prem?
    Ans: Leave the pending amendment in normal process and the new extension in premium. Once the new extension is approved, withdraw the pending amendment.

(FYI: There is no combo of amendment&extension. When you are filing extension, you can change the work location etc on the extension papers itself.)