In point 7 of the Hunting Grounds/[사냥터] section it says indeed only that the old Bosses will be removed and replaced with 10 new ones. In the Powerbook Wikipedia Baium etc. have already been updated to 118: http://lineage2.plaync.com/gameinfo/raid/index?searchType=1&serverId=53&beginLevel=118&endLevel=118
On that lvl 118 list the new Bosses are missing, but you also don't find them when you search for them by name, i.e. they have not yet been added to the database. We simply don't know what level they will be.
As far as the looting rights are concerned, it sounds indeed as if only the last hit gets the loot. The problem is that if there is a party or a command channel (파티 resp. 연합), that also applies. In other words, if anybody out of a command channel does the last hit, the looting rights go to the command channel. In theory a solo player could ninja the loot by trying to get a last hit in before the Boss dies. But with 20 other players attacking, the probability for that, esp. with a high-level Boss, is rather low.
To put it another way, the more members there are in a command channel attacking a Boss, the higher the probability that said command channel gets the loot. This sort of elminiates the advantage that extremely well equipped solo players have right now. Advantage is now given to big groups, even if they are not so well equipped