A. You have exposition points attached to your account that will let you add more parcels to a settlement. Although you own all the land in the county, you simply can't "add" a parcel to the community because your community does not have the population to populate it. If you have the population to populate that parcel, then you can do freely.

B. Anyone (NPC or players) can "steal" land from you by building a single building on the parcel. It is up to you whether to "kick" them out or "let" them stay. Even if they "steal" the land from you (using the word steal because they have to purchase the land from you normally) they will pay the taxes of the county .

C. The count should technically hold every and all control to the lands within the county.

D. If the holdings is a part of the settlement, and the count loses his rights to the capital of his county (the settlement in question where his holdings are), then the count will lose the holdings in the settlement as it is a part of the settlement, which he lost via CB. If the count has holdings outside of the settlement he lost, or outside of the county he lost, then his status will simply revert to "gentry" with holdings that the CB cannot or does not refer to.