Those things are present, but in a rudimentary state. It's certainly not what you buy the game for. You can however, own a castle or even a city. In short:
- Interesting combat system, and on horseback!
- You can fight in a war, along with your king in pretty big battles.
- Or you can fight in tournaments, a good way to raise money.
- You can also back a claimant to the throne (never tried that).
- You have a reputation with each lord, which can increase if you release them after capturing them, or if you do a quest for them (but there are only a handful of quests, which keep repeating and they're not always interesting).
- There are 5 factions with different types of soldiers, you can hire mercenaries in cities or peasants in villages that belong to your faction or that like you enough. If those soldiers get enough experience, you can upgrade them, but you'll also have to pay them more.
- You can level up your character rpg-style. There are combat and non-combat abilities to choose from.
- There are full conversion mods (I never tried any though).
- There's a stand-alone expansion coming, with multiplayer:
http://www.taleworlds.com/main.aspx
You can off course, download a demo from their site to check for yourself.