First you go to ITunes and buy the music you want. Then go to Music and you can hear your music there
Plug it into itunes and sync it. If the songs werent on itunes then theres no chance unless you download them again.
Unless you "Transferred Purchases" to your iTunes or made a backup of your iPod, there is ABSOLUTELY no way to.
Yes, restoring your iPod will clear all contents on your iPod.
Yes, but you can sync them back
going back to default settings
No, restoring an iDevice wipes everything
You need to back up your iPod on your computer before you restore it.
Restoring an Apple Device takes it back to factory settings so yes, it wipes the device's previous data. Best to back it up before restoring
you can't, but there is this program called iPod rip. but i doubt it works with the new firmwares apple uses on their iPods.
You back it up on itunes, then reload it again
Yes, restoring your iPod will take off the jailbreak, and you will have to jailbreak it again.
Of course...by restoring the ipod.
What you are doing is 'syncing', and every time you sync your iPod, it will back it up. If you do not want to back up your iPod, highlight the music from your library that you want to put on the iPod and just drag it onto the iPod Touch menu.