Job Change after 6 years of H1b

My H1B 6 year term completed. My i140 approved(before 3 years). I got an extension of 3 years on the basis of approved i140. Now I have received a new job offer. My new employer is ready to file my green card only after 12 months. Now my query is

  1. If my I change or fire from the new employment before approving new i140, can I apply for a new job on the basis of approved i140?
  2. Will I be exempt from the H1B yearly quote ?
  3. In such occurrence, Do I have any other way to keep my H1B/i140 ?

Yes. Once I-140 is approved for more than 180 days, it can be used to any future AC21 extension of H1B.

Yes.

Don’t understand your question, please clarify/elaborate.