hey guys

i have lots of documents, music and graphics on my computer
but i also noticed that i don't have some of the iLife programs, and as i understand i need to reinstall OS X, and the best way for me is Archive
but i need to hear from you, what will happen to my documents? and the freeware? will i need to back up everything to another drive, and reinstall the freeware?
what is archive?
what about all the passwords? history in the internet and bookmarks?

thanks in advance