It really matters on the updates, maps, mods etc you have.
and if you are including the memory taken by Steam (which isn't very much)
Everyone has to download pretty much the same amount. The earlier you download it, the more updates you go through. The later you download it, the more you have to download due to updates. Currently, 18/03/2012, there is approximately 11-12GB amount of downloading required to download the game entirely from the beginning.
Team Fortress 2 requires 5 GB of HDD Space to operate.
9.5 gigs
Maximum is 32 on each team.
As of 27/04/2012 there are 540 items in team Fortress 2.
Team Fortress 2 is free to play, so you can download and install it onto as many computers as you like.
There are 1024 megabites in 1 gigabite. 20 gigabites has 20,480 megabites.
1024
It depends on how many gigabites it has like 8 gigabites can hold about 15 movies.
5500
4,000,000,000
None
4500
check on www.youtube.com and put how to put skins on team fortress 2 if your not allow on youtube go to google videos and see for your self
1.306728 gb