yes you idiot what do you think
No
yes,i need
You don't need to buy Skyrim from Steam, but it does need to be linked to your Steam account (by registering the serial code you should have got with the game).
You at least would need : 6GB RAM (8GB Would be so much better) NVIDiA Graphics card ... I Recommend Alienware laptops or Desktops
Usually, to get married in Skyrim, you will need to do a quest for the person you are trying to marry.
It should tell you if you need to update
Not necessarily. You might need it to instal it, if you don't have the disk along with Skyrim when you bought it. But once it's installed, you can play offline same as you can play regular Skyrim offline.
If you like role playing games and have a decent to higher-end computer(if you are playing on pc). Skyrim is one fo the coolest RPGs I have ever played, but a pretty decent graphics card(for pc) and proccessing capabilites are necessary to appreciate the full artwork that is Skyrim.
Dawnguard is basically an expansion pack for skyrim. like all expansion packs, it requires the base game to play. So on a PC (and any other gaming device) you need skyrim first and then you can install dawnguard.
If you need a claw to open it, check to palm of the claw in your inventory. If not, look it up on cheatcodecentral.com or any Skyrim forum.
dsd
Definitely an intel core quad q6600. I tried running it on an intel core 2 duo, it was okay, but the frame rate was terrible.