i am really really old so my icq number indeed has only 8 digits.
sharing parts of the core code won't be possible (it's an all-or-nothing type of code), but i am using a few things like pathfinding, aiming, projectile evading (ai stuff) which i can share. also, i can inaugurate you into the secrets of the hhexen-engine which has never troubled me when i wanted to add some features or behaviour to the entities in the game (imho the main design is a piece of art).
sharing models: there are lots of free trees, plants and monsters which i could provide.
for our selfmade models, you should ask my faithful disciple yunus (who has a jme forum account)
what i wanted to add to hhexen for a long time now is arms/hands of the player, making naruto-like hand signs while casing a spell. the arm model is done, but the animations are missing. no one had the skill and/or time to make them.
if this is your first big game, i can provide some design secrets in exchange. just tell me how you are planning to do something, and i will comment it sensibly.