I heard nanos and iPod Mini's are no longer being made?? This distresses me! Someone tell me it's not true.
Just to clarify on this point, the iPod Mini has been superceded by the iPod Nano. The former is no longer in production, but the latter will be with us for some time to come.
I have never uninstalled iTunes, but I have upgraded it on many occassions and my music library has stayed intact. Your music library will be in your home folder, and uninstalling iTunes should only affect items in the library or applications folders.
Nevertheless, whenever there is a shadow of doubt (and even when there's not), you should ensure that you have an up to date backup on hand.