1 - Not officially, but the Sven Coop mod is already working on it.
2 - From the get go you have counterstrike and day of defeat. I'm sure most of the other popular mods like Natural Selection and the like will be on the way as well.
Halflife 2's story really has me interested, the videos have left me with nothing but more questions(i'm not asking for spoliers, I'll wait for the game, please don't post any).