No, updating an iPod will not delete anything on your iPod.
no
you press the delete botton
You cannot delete songs directly from iPod Touch. You must connect it to iTunes. Go to the music section of your iPod and right mouse click on the songs you want to delete and click delete. Then, safely eject it through iTunes to make sure the process will work.
no
unfortunatly there is no way to delete songs from the iPod touch itself to delete songs you need to do it through iTunes.
You have to delete the songs from iTunes on your computer first,then sync your songs.
You must connect your iPod and open up iTunes, and delete the song from there, then sync the iPod.
Yes;0
You can do it on iTunes from your PC
Yes.
Yes, you can delete songs off of a jailbroken iPod Touch (but only through iTunes).