Yes, Skyrim was available to purchase and download from Steam on 11/11/11. Even hard copies of Skyrim had to be authenticated on Steam.
If the patch has been released, Steam will automatically update the game when you launch it.
It is supposed to be released November 11, 2011.
Buy it through the Elder Scrolls website, Steam, Xbox marketplace, or the Playstation Store.
You can find it on Steam.
Yes, you can, it is available on Steam.
You can download it from services like Steam, direct2drive and Impulsedriven. If you plan on modding the game, I suggest you download from Steam.
You can do what you want in Skyrim, attain any level, max out any skill, you won't miss anything from the Dawnguard expansion pack. It is already out for PC also as a disk version, though it's easier to get it through Steam.
The GOTY edition is available on Steam.
You can fix Skyrim on steam by removing all mods and Workshop content from your game before calling Skyrim support.
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).
Steam's mandatory for Skyrim, for both disc and digital versions. If you've uninstalled Steam, you'll need to reinstall it, and get the patch from there.
You can purchase The Elder Scrolls IV: Oblivion for the PC for download from retailers such as Amazon or from digital distribution platforms such as Steam.