If by some coincidence a player has 11 characters on 2 realms that are to be connected, say one of each class in each faction, would that player effectively end up having 22 characters on one realm ?
Given the data in the Connected Realms sticky (good read, by the way), yes. In fact, in theory, someone could put 50 characters (account maximum) on a connected realm, which would compose of 5 (or more) realms.