Hello my friend I'll be happy to answer any questions :)
So lets start.
1)Yeah every castle has its own passive buff that grants the owner and the clan members with statistics like Critical Damage + P attack, Pdef + Run Speed and etc depending on class of course.
The owner of rune's castle will gain additional adena from all the other towns like adens castle dats why our main town is Rune village and our temporary starting place is Rune Harbor (Rune harbor is also our exhance/trade area) So your crest will be applied on every npc in your commanding region. There will be a reward box that will give random prizes to all members of clan.
2) Yeah fortress of the dead is siegable every Monday and Friday.
`Thanks :)