When did you applied for I-140? The cut off date for using substitute labor certification was sometime in mid July 2007.
Your H-1B application will not affect the I-140 processing, and it is not required for you to stick to your employer 6 months after I-140 approval. But yes, I would suggest you to wait for I-140 approval before changing jobs. As long as your I-485 is pending for more than 6 months (preferably with I-140 approved), you are covered by AC21 criteria.
Your wife may continue to work on EAD (as long as the GC process is on). This is not employer dependent. Also, you are not required to inform the USCIS about your job change, but must be prepared to answer any queries about the I-485 application.