I bought the iPod Touch 2g 8GB about 2 years ago and I now want the iPod Touch 4g 32GB. Is there a way that all the apps and music I bought on the iPod Touch 2g can be transferred to the new one I will buy?
Yes - I had to do this for the same devices: 2G to 4G. I think I just synced the new iPod Touch (there is no such thing as an iTouch) with iTunes, and everything went over, but I might have had to restore a backup from the old to the new.
With the new iCloud, once you download any app from the App Store, you can retrieve it from any device. The only requirement is that you're logged in as the same Apple user who downloaded the app.