As for the Hanoverians, only a few of their flags are known.
See the following TMP discussion for a booklet (posted by Steven H Smith) detailing them.

http://theminiaturespage.com/boards/msg.mv?id=76780

Also see Sotheby's auction:

http://browse.sothebys.com/?cat=1&count=20&dp=Arms+and+Armour&event_id=27489&g=1&hp=&hpc=&i=1&is_past=1&page=44&sale_id=MM0986&slabrowsesort=lot_sort_number&u1=dp&v=l

Item 4417 is the Hoya Regt. flag and item 4418 is the Calenburg Regt.
As I recall these two weren't with Wallmoden but they will give an idea of how the Hanoverian flags might have looked.

Cliff McLeod