1. I am curruntly on HIB Visa for the past 5yrs and 2 months (GC process started and 1-140 approved) working for a State Health Department.
F Visa - What is it?
This is upto the discretion of the consulate and then again upto CBP when you land in USA. Consulates have the discretion to issue you a B visa - despite your presumed immigrant intent - if they are convinced that you will return. This is true for all cases where a B (or F or similar) visa is sought while GC is pending or could be pending.
The two-year home residency requirement does not prohibit issuance of F-1 visa. That can be tried any time, even before the HRR is completed. Ultimately, F-1 visas are discretionary. But there is no law that prohibits their issuance in these circumstances.
Issuance of an F-1 does NOT waive the HRR. You will stay subject to it.