More newbie questions...

[part_time_player]

Still trying to get my head around the new units, building tree etc...

Started an English campaign in High era. Selected Nottingham and looked at the description cards for the buildings there:
Citadel (Allows; Dism English Milites, Dism Feudal milites, Milites Familiares)
Barons Stables (Allows; Feudal milites, Milites, Hobilars)
Barracks (Allows; Feudal swordsmen, Billmen, Servientes Loricati, Norman Sergeants, Servientes Armorum, Peasant levies)
Encastellation (Allows; Arriere Ban Levies)

Problem is, my recruitment options do not allow for the dism Eng/Feudal milites, Feudal Milites, Feudal Swordsmen or Billmen.

So my questions are:
Why can't I build these troops in that settlement?
Why does it have barracks and barons stables anyway when these require seigneur estates to be built?
Is it right that the units are called milites, servientes etc instead of Knights and Sergeants?

Any help always much appreciated!

#EDIT -1 more question, how can I recruit Norman Sergeant Archers? I start off with 5 units of them but it seems I skip from peasant archers straight to longbowmen?
#EDIT - Ok, I can build them in a high level town watch once I get to city size, just realised that the building browser doesn't update the units available on buildings until you pass certain milestones

[Consulo]

Additionally, you can be playing the Early Era campaign for all it matters, have a fully upgraded citadel and not be able to recruit all the units. There are time period markers that allow for new units to be recruited from what I understand. Same with High and Late eras. Gun Powder weaponry is a good example. You can build cannon foundries before you can actually produce them I think. If I'm mistaken, someone please speak up.