@Rafnel, regarding "other", my 2c worth of observations: If you run your iThing close to full then an app installation (new or update) that fails due to lack of space can leave detritus in "other". Half-got .ipa, half-done installation - I don't know, just detritus. The best thing to do is to delete the app off the iThing, make more space for it, and install it afresh. Of course this loses saved data though. The alternative is to make an iTunes backup for the iThing, then reset the iThing utterly and resore it from the backup. This often recovers junk "other" space.
If you do an app update wireless then I believe the max iThing space usage is .ipa + old decompressed app + new decompressed app. If wired to iTunes PC then it seems to be minus the .ipa. So wired is lighter. If you delete the old app first (losing saved data) then it is lighter still.
I think some people leave a gig or so free to avoid issues like this. Kinda tough on an "8gb" iPod. I think you'd just best be circumspect about what apps you install and update. (Especially update.)