I applied I-140 before with my previous employer in EB-3 category. Can I keep my priority date after a job change and with a new EB2 NIW application thereafter?

Also, my wife also applied in EB-3 category before. Can I use her priority date to apply for I-485, if my NIW application gets approved later? 

Many people confuses the rule of priority date transfer in the immigration proceedings. The priority date of employment-based immigrant petition is retained only after the I-140 petition is approved, and then the alien beneficiary of multiple approved I-140 petitions can claim the earliest priority date in the I-485 application proceedings.

The retained priority date is limited to the "individual" alien beneficiary only, and cannot be transferred to other individuals including the spouse, even if the spouse has another approved I-140 petition.