shugsy
the iPod will come with a disc
iTunes also requires quicktime (all free) and if it's not on the disc you'll be pointed to the website prob'ly
it creates a folder that holds your tunes and a file that works as the database of all the contents of your music library - ie the iTunes player
each time you have iTunes open and put a CD in your drive it will prompt you to download/rip the album and in doing so, it creates a folder for the artist and inside that, a folder for the album etc etc.
if you're getting your files from 'elsewhere' then you need to add the folder to your artist/album folder set-up and then drag the contents to your iTunes player before you can play it. iTunes can play most things - even midi files, (and convert to formats including wav files etc....)
as monty suggested, you can then create 'playlists' (compilations/mixes etc) - and burn CDs from these.
it's up to you whether you control what goes on to your iPod by automatically syncing with the contents of your computer's library of tunes or whether you want to add specific tracks manually.
similarly, it's quite easy to choose what sort of format you want to rip your CDs to. whatever the music boffs say, it's all listenable. especially if the tracks are mostly new order bootlegs recorded through someone's hat.
the thing to bear in mind is that all these tracks go on to the iPod via your PC so even if the iPod is 80Gb then your PC is going to get quite full - especially if you have it set to automatically sync and have a 'lossless' format selected
if you need to be talked down give me a call in air traffic control