I have an EAD expiring Nov 2010, GC EB3 PD 2006. I lost my job. I want to go back to home country(india) but I want my GC processing to continue. Is this possible?

if yes, is there any requirement like I have to come back to US in every 6 months or I have to keep paying taxes or be employed by a US company at all times while outside US?

Do I have to have a US job before I enter US on AP?
For how long can I go to india? Can I work in my india with a non US employer?

do I have to file AC21 every time I change employer when AOS pending?

I started using EAD 6 months back, before that my I was on H1b, my previous employer probably revoked H1b. Is my visa still valid though? If I want to use the same H1b 1-2 years from now can I do that by asking my new employer to reapply H1b?