Best wishes to you.....
1. When can I request the I-485 transfer?
After EB1OR I-140 approval.
2. When I-485 is transfered, what is the priority date, old I-140 priority date (5/4/2005) or new I-140 priority date?
I think it should be the new EB1OR PD date. But it doesn't matter now because EB-1 is still current.
3. Do I need to request priority date transfer from old I-140 to new I-140?
Don't know.