The setup you have posted will be perfect. Pi 3 has more computing power and wifi functionality.
This is the way i did things with my second feeder.
Set it up. Get on the exact same network with it. Open the browser on your computer. Log in to your FA account. Then type in the second feeder (raspberry pi) address into you browser address bar. Click Claim feeder button and you are all set.
I was wondering how… I was to find the address so I just went to my router and found the piaware and the address for it entered the site address and then it went to flightaware and I chose to claim it!!