each hotel has its own bus...they come about every 10 minutes..they start running an hour befor park opening and stop running i believe an hour after park closing
i also heard about these parade changes...i arrive in WDW on Aug 8th which is 4 days away so im definatly going to see if the parade changes on the 10th
you probably should get your wristband as quick as possible on the nights when you see big crowds...just to make sure that you actually get one and they dont run out..im pretty sure you could get one after park closing though