Welcome to UU, Jay.
I bought my first uke years ago, but put it aside without accomplishing much. I recently picked it back up a few months ago with the intention of practicing every day and making a real go of it. I can strum chords for popular songs and sing along, but I wanted to get a bit deeper with different techniques-finger picking, chord melody, single note playing, etc.
I will +1 the Ukulele Aerobics book. I recently started it, and it is great. It provides a little more structure than a lot of "How to play ukulele" books, and it also gives a good variety of different techniques. It teaches chords, strumming, fingerpicking, chord melody, single notes, licks, and various left hand techniques.
As for the callouses, they will no doubt come in time. I am also a banjo player, trying to get back in the saddle and rebuild my calluses after about a 6 month hiatus. There are various things you can to do build them up faster (a quick google search will help with this). For myself, I soak my finger tips in rubbing alcohol to help expedite the process. Also, steel strings will get you there way faster than nylon/nylgut strings.
Good luck!