A full changelog at this point, compared to DV vanilla, would be almost impossible to do. Other than the incremental changelogs, there's nothing I can give you but the main points:
*) added cultures: croatian, serbian, bulgarian, vlach, berber, nubian
*) all scenarios updated for historical accuracy and new cultures
*) dynasties revised for historical accuracy
*) multiple bugfixes to events
*) added events for laws, melting pots, bugfixes, and to guide the AI to conquer historic realms
additionally in the addon:
*) replaced monastic supremacy with a female inheritance law (full cognatic primogeniture)
*) revised scenarios to take female inheritance into account
*) added and changed events for female inheritance
*) added events to break up larger realms
*) added events to spawn historic realms over time
*) added the Bopack event mod
*) added the 1204 "Fourth Crusade" scenario
*) added several recreatable kingdoms: Navarra, Nubia, Brittany, Mann and the Isles, Aquitaine, Lotharingia
*) Added Knight Orders: Order of Santiago and Livonian Order
But by far most changes compared to vanilla are in the scenario setup, with new, changed, and replaced characters; new, changed, and replaced countries, changes to owned titles, changes to owned relationships, changes to owned dynasties, etc.. This really would be impossible to list compared to vanilla since the scenarios are almost completely changed.
DVIP Wales is an implementation of DVIP+Addon on Kurek's Welsh map mod:
http://forum.paradoxplaza.com/forum/showthread.php?t=367544
A kingdom, duchy, and culture map are possible, but would need to be updated. I don't know when I'll have time for it.