Filed GC in EB3 category -B.E degree with 8yrs of experience in 2003 now 14+ yrs

Labor 10/03 & I-140 approved

I-485 date 10/07
Got EAD but not used

I came to know that part of my company operation got sold to another company.

Questions:
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If receive an offer from the buying company. let me know the steps to maintain my GC?

Whether can work in buying company with my current H1-B visa.Whether any paper work to be done for it?

If receive new H1-B approval with the new company? Whether again to be stamped in my passport?

If got layoff. Within how many days i will be out of H1B status?

Whether my case can be converted from EB3 to EB2? or conuslor processing? What is the procedure for it?

If my wife uses EAD & work.Whether that affect my H1-B status?