Welcome! Where about are you in PA? I always recommend hooking up with a uke club if possible. If you're close-ish to York or Lancaster, you have the Central PA Uke Club and Ukulele Uprising respectively. If you're closer to Altoona, there's the Allegheny Ukulele Kollective (my club), and if you're closer to Philly, the Mainline uke club has jams all over the place!
I suggest going to a local music store and trying out all the different sizes to see what "fits" you best
I think concert scale is best for learning on - inevitably, you will likely buy more,
it is called Ukulele Aquisition Syndrome (UAS), a well know affliction.
Welcome, MEngler! I used to live in York -- I graduated from YCP. In fact, I was just up in York for a ukulele concert on Nov. 19th. Hope you find one that you're excited for.