I know it's been asked and I apologize but there are so many threads and I want to be sure.
I can make FP + reservations but can I also get FP at kiosks in the park once I use mine up?
I believe you are correct. Like you I have been a little confused on this and will be entering into the world of FP+ for the first time next week. But it seems like once you use your 3 FP+ slots! you can head to a kiosk and order a 4th. After that you can try for a 5th.
That is correct. The last I knew in June, as long as you didn't no-show all three you could start making additional selections at the kiosks after the third. The additional selections at the kiosks can only be made for the park they are in.