fortress: baslista bomb, capture rope, books for enchant skills, potions
can't remember the exact names because a long time has passed since I played on a server which has working fortress
but if you want to see what you can buy go at the gate of a fortress and speak with the npc there
some items are bought with adena while some are bought with some kind of reputation points earned by having ownership of fortress
and about the castle well I forgot
but I am sure you can buy castle aghations and the castle circlet