Sounds like you've made some choices but let me add a few things. First, find out what caliber is most carried in your area and dept. and go with that. You can learn to handle almost anything but "common caliber" is not something to be tossed out lightly. Around here, .40 is KING, so anyone needing extra ammo with a 9mm is going to be out of luck!
A note on the Glocks, I'm not conversant with all the reasons for the KB's (and from what I've seen, neither is the factory) but it is something to take into account especially since, if you want to stay safe, you'll need to put in a lot of range time with one outside of qualifications. I used to be interested in having one until a friend a another PD had a Glock KB. He's still having surgeries on that hand. Many carry and shoot them for years without problems. Your call.
In any event, welcome to the family. Remember to learn EVERYTHING you can from the older cops in your area, wear your vest ALWAYS when on duty and while being friendly to everyone, don't trust them too far.
HTH,
Mike