Yes, copy IOS images to all the stack member switches flash by using copy tftp: flash1:copy tftp: flash2:
.... etcNow boot all the flash by using boot system switch all flash:/and write the image... write memeory.verify OS images by issuing the comma...
Yes, you can configure priority on the new master before conencting.Use command : switch priority < new-priority-value>Make sure you are giving a value which is higher than current master.