iCloud is not a storage service, it's basically a syncing and backup service. If you need off-site storage, I'd suggest getting a free Dropbox account and sync files to that. For music, you need to subscribe to iTunes Match in order to store music on the cloud. You can delete apps any time and later get them from the iTunes store for free (assuming you bought them earlier).
But the bottom line is, if you want to off-load files to save space on the iPad, icloud is not what you want.
I already have iTunes Match.
I don't trust in dropbox.
I love iCloud. I love Apple. I loved idisk. I just want to understand how it works.
I'm afraid of syncing… Many people lose their stuff.
In Macworld Mag… there's a article about upload files to iCloud, have more than 25.000 songs on iTunes Match and so one.
MobileMe was not perfect… I cloud could be.
The iCloud system is not too clear for many people.