"will first three be somehow different from those, that are available already?"
That depends on how different you want to make them! Fulford could include the Northumbrian General Levy, Hereward though Is a long shot but could be a rebel, outlaw and civilian set ... Edwin and Morkere were pivotal to the events of 1066 and long after... for a short overview see:
"We also thought about mounted Saxons and Vikings but found no reasonable use for
A large number of the English would have been mounted, no army could have travelled the distances that Harold did in the time he did without a large number of horses..
So an English Army on the March, forget the ox wagons too slow, include pack horses not mules... Pre battle mounted, Parley, persuing an enemy mounted, fleeing from an enemy mounted, scouting, messengers... even Raiding...
Vikings.. or the Norse would aquire horses as quickly as possible for travel, foraging, scouting, raiding etc as well...
"We were thinking along some more non trivial subjects, yet within the mainstream of the conquest event, say:
- Doomsday Book
- War council before the battle
- Allegiance oath of Saxon noblemen
- Royal feast
All in Big Box format."
Doomsday book and Allegiance may well be very similar..
Royal feast? not sure the English had anything to be particularly happy about..
The best idea is the War Council which could include an Allegience scenario(Edwin and Morkere/Harold, Harold/William, Edwin and Morkere/William are all possible) and a mounted parley with the enemy...