Just wondering, and sorry if this has been discussed already, but im assuming PvP isnt just going to be limited to Cyrodiil. Im not completely sure on that, ive asked around with no answers, but i assume not. So when all the lands are active in the full game, can u go from dagger fall to skyrim? or blackmarsh to elswyre? i just wanna know if u can cross into enemy provinces.

Cyrodiil is the only PvP zone. You can enter other alliances territories post-50 as part of the Veteran content, but doing so is purely PvE.