H1 Visa transfer and ammendment request in process with old employer

I am currently working for employer A and got offer from employer B. Employer B is filing my h1B transfer case while employer A has to file an ammendment request which was due as my location got changed after initial visa stamping?

So I have below questions :-

  1. Is there any impact of not filing an amendment on my new petition (H1B visa transfer)?
  2. Can I join new employer before i receive approval notice for amendment request petition?