I see in the other players' names something like "heir, vassal etc.". What are these, what benefits does the player has and what do we need to do in order to reach in that situation? I prefer to put it from the best to the worst.

I guess you ask about the game cause in the forum we also use it as rangs but there is nothing to do with the game idea.

Player Ranks

Player ranks are based on a character’s social status and clan activities.

* Ranks are applied according to a character’s clan status, clan level, and position in the clan.
* Players can see their own rank in the character status window. Players can see the target’s rank in the Target window when another player is selected.
* Heroes and Noblesse characters may attain special class ranks regardless of clan status.


Here you can read detailed info about
Vagabond
Vassal
Heir
Knight
Elder
Baron
Viscount
Count
Marquis

http://www.lineage2.com/Knowledge/clans.html

So, that doesn't influence the gameplay I think. Thanks a LOT.

Some clan skill work only on knight for exemple. Or the Apella Set can be exclusively worn by a baron ( if i'm not wrong ... but who's got the Apella ? The FW is better :p )