Hello there Gummy Bear. As you can see in the video, we did a bit of testing with group stuffs. I can say this for definite:
A: Kill credit IS shared. If i kill a mob and another member of my party needs the kill for a quest. They get it.
B: EXP IS shared. If i kill a high level mob then the lowbie players get good exp from it, Yay for Power Leveling ^.^ However, If a high level player is in the party, then the higher level player steals the lower level player's general exp
(Keep this in!!!)
C: Loot is NOT shared. As you can see in the video, my friend Thor kept getting voicy about people stealing his drops
And at one point ClassicLover said "Well we'll just have to kill twice as many"
Hope this helps, we'll do a bit more testing on this in the future, and upload some more vids, in better quality (The quality was recorded in 1080p HD but rushed onto youtube and rendered fast (Cus i wanted it up fast) and therefore put up in poorer quality (Going off topic)
Some more things:
They aren't "Immortal" they just don't dissappear. All drops and correct rewards are given, they just stay there until you leave the area.