I am working in USA from about 8 years on H1b Visa .For about last 5 years I am working for same employer and they filed my GC in EB3 My Priority Date is 08/2006. labour and I 140 is approved. My H1b extesnion is in process.
I have another GC's pending. which is through my husband GC( EB3 PD 4/2004). and I have filed I 485 as dependent. I have got EAD but not using ead till now.

I have got a job offer from another company.
question:
1. Is it possible I join the new company on my EAD card based on husband GC but have new company file for a new GC for me in EB2 category and still keep my old PD date of 08/2006. if yes, what is required to make Eb3-->Eb2 ,keeping old PD on new job. while working on ead
2.what is best legal way for me to join new company? H1b xfer/EAD/new GC in eb2.