As to ancient lore: The trait can be purchased in the warrior guild and the wizard guild. I believe they are available once you have level three guild standing. Once you have that trait you will be able to train the artefact skill. If you can already train that skill it is because you already have the trait.
As to finding the way to Ishad N'ha: Check out
Xignal's Site. There you will find maps and all other sorts of useful things. Basically, though, you have to follow the river until you get to a giant cave. To get through the cave you must wear the holy signet found in the crypt. Then you will get to Ishad N'ha.
As to the Sword of Mastus quest: You will often get a quest where you must retrieve an item. When delivering the item all characters will get the reward if they have all undertaken the quest!
It goes as follows: Once you deliver the item the character delivering it will get experience points + guild promotion. Then click on another player and that player will receive the same, although the guildmaster's speech will differ a bit. There are a few quests which also carry a reward in the form of gold pieces. There you will only get the gold once, but the other characters will still get the rest.