You can sort by 'last log' on the geocaching.com your trackable page, which will put the ones that haven't been logged recently at the bottom, and will reverse it if you click it again. One thing to note is that the sort by is above the table.
This may help for number one, and the chances are that the ones at the bottom will be most of the unknown location ones. This page lists all your trackables, so you could look through the list and see which ones are marked in the location field as 'unknown'.