I think it depends on whether they are held in europe or the US, there are different traditions and formats.

Some play a 7/8 year game (so up until the end of 1907/8) with players aiming to get the highest SC count on that board - with 'topping the board' being the best result (i think this format is popular in france). Then after ~3 hours of play you move onto a second board and hopefully get several games in through the tournament (maybe 1 on the friday night, 3 on the saturday and 1 on the sunday morning) The the best 7 scores from the tournament play the top board on sunday afternoon...

I think the US tournaments are more inclined towards solo-ing and full games, but only getting to play two. But each tourney will have it's own rules spelt out.

Things are very different in person, mostly because you can see who is talking to whom, if the first person england goes to talk to each turn is france then you can guess that they've got an alliance (though they may be arguing a lot).

I think that anyone can enter, but there are some international rankings so you may be seeded as a noob if you don't have a ranking, again the tournament rules will dictate what board you are placed on, which may mean there is one noob on every table to begin with. (also some metagaming may occur, where players who know each other from many different tournaments and by reputation will use that information and may assume that since they don't know you you're an easy kill...)

I highly recommend finding 6 friends and playing face-to-face with them; (even if you just play up until 1907 and then get pizza&beer) It is a rather enjoyable evening with the right people and should set you up for at least some of the difference in what to expect from a face-to-face tournament.

As for where you find things out, try: http://www.thenadf.org/grandprix/2012-grand-prix-schedule
or: http://www.diplom.org/Face/cons/index.php