PERM Audit Processing Time shows the date PERM was filed?
Yes, the date shown on PERM Audit processing time is that date and month that your original PERM case was filed.
So, if you case was filed in Nov 2017 and you received Audit in May 2018, you will still count Nov 2017 as your filing date for PERM audit.
Filing PERM again after rejection and H1B extension beyond 6 years?
Yes, you can apply H1B extension under AC 21 if the PERM is pending for 365+ days at the end of your H1B 6th year.
You can also re-claim your time spent outside USA if the time between your PERM filing and H1B’s last day in 6th year is falling short of 365 days.
Normally, this is a clever strategy that people use if the short fall is about 1-60 days (depending on how long you have stayed out of USA).
You can count the number of days you were outside USA during your H1B and then file for extension in 6th year.
This will help push your 6th year dates forward and may make you eligible for AC21 if your company is not able to timely file PERM in Sep 2019.