US Electoral system

Would someone please educate me on what the US "electoral college" is and what it does?  I'm confused.  In the UK it's different.  You vote for your local chap, and whichever party gets the most local chaps elected gets to play Government for four years. Those local chaps go the the House of Commons and yell at the PM during Prime Minister's Question Time, the best part of British politics.  Question Time is a free for all where everyone gets to sling questions at the PM and he or she has to try and answer on the spot, moderated by the Speaker of the House.  It can get quite rowdy, all those "Here, here!" rumbles from the back benches.  The PM and Cabinet sit on the front benches, directly opposite the Opposition Leader and the Shadow Cabinet, more than a swords length apart just in case.  The Commons is one stage of Parliament, the next tier is the House of Lords, which are not elected.  We're generally just stuck with them since they're Hereditary Peers.  Laws have to be approved by the Commons, then the Lords, then the Queen.  She could veto the law, but it never happens.  The day after the election you clear out your office if you lost so the new chap can move in.

But in the US, as far as I can gather, you elect local chaps both to Congress, and the Senate, so you're not stuck with any hereditary anything.  After that I get a bit hazy.  How do you decide who won?  What's the difference between Congress and the Senate?  The only US Election I've watched was the 2000 one, so forgive the confusion.  Why the month of hanging around once the election is done?  If the government has changed, why not get it over with?  Who do you vote for if you hate both parties?  Why are there only two parties to chose from?  I'm going to have to know this for my civics exam one day so I'd appreciate the info.