When created, aux returns don't show up by default in the arrange window in Logic.
To add them, select them in the mixer and either control (or right) click and 'create track', or hit the key command. ('control+T' on my system).
AFA rearranging the mixer: The order of the channels in the mix window are dependent on the order in the arrange window. Change them there (click and drag) and your mixer will update, provided you have "Tracks" view selected.
The ability to rearrange tracks directly in the mixer has been a longstanding request by many users.
Hope that helps.