good questions... will need the answers to give a more specific reply, but here's another thought too...
4 months is a big developmental time, and many babies wake (at 4am!) to practice their new skills. she may be doing that now. you can either ride it out, or you may want to try wake-to-sleep & see if that helps.
i agree, if she didn't need night feedings before, you will want to cut it now.