War Scholar: At the War Scholar you can enter the menu for Doctrines, Battle Relics, Auxiliary Units and Mercenaries. If you press 'x' you can open the same menu, so you dont need to go to that NPC.
Sheriff: At the Sheriff you can open the Matching manu (or just press 'j'). In the matching menu you can enter the queue for battles. In Addition to that, you accept the three important Daily Quests, which can give you up to 1200 extra honour every day.
Warden: At the warden you can open the fief overview menu. You can open it from the world map too by clicking on the town and choosing the city-symbol. The daily quest In Service To The Realm can be accepted here.
Billeting Officer: The Billerting Officer is one of the more important NPCs. You can accept some quests here, open your Barracks (or just press 'u'), join the Unit Training place and open your supply dump (you can open your supply dump from your inventory too).
Master-at-Arms: Here you can join the training yard and unlock new weapon skills (or just press 'p' and go to Skills).
Watchman: At the watchman you can leave a fief.
Hall of Fame: The Hall of Fame is what it always is. Here you find the best players / houses / alliances. You can also place massages at the Massage Board of the fief.
Town Crier: Nothing
Unit Weaponsmith: At the Unit Weaponsmith you craft Unit Kits. You can't craft every Unit Kit in every town!
Refinery Overseer: Here you can refine your gathered Resources to materials.
Artillery Craftsman: At the Artillery Craftsman you can build green/blue/purple artillery with your refined materials.
Smith: Here you can craft weapons and armour for your own or for your horses and salvage useless items to get more crafting materials.
Armourer: The Armourer sells cheap weapons and hero armour, but he can recondition your used armour, if you have a really good one.
Artisan: Here you can alter your equipment appearance or salvage attire or exchange attire.
Auctioneer: At the Auctioneer you can enter the Item & Resource Market (or just press 'v').
Horse Seller: Here you can buy equipment for your horse, new horses, Hay to feed your horses if needed and join the Riding School.
Smuggler: The smuggler sells white crafting materials and Personal Storage Expansion for 200k silver coins.