Plug-in your iPod. Right-click on it in "Drives & Devices" and select "Options". You'll see a list of playlists. Click on the list to sync the list contents to your iPod on the next sync.
Regarding a playlist that swaps out content: I have a playlist that I call "Favs Not Played Recently". It is a smartlist of songs with 4-5 stars that I haven't played in the last week. I haven't really watched it closely, but MC does appear to be moving songs off the iPod and replacing them with new content as the smartlist updates (not sure if an iPod play counts or if it is just using MC plays).
So, for your example, create a smartlist of two hours of music that hasn't been played in the last xx days. Then select this smartlist in your iPod options.
Make sure to check "Delete from handheld any files not in sync list" in your iPod options.