1 hour with the GO Plus and I can confirm this:
-Yes, it tracks Eggs & Buddy with the game in the background
-Contrary to reports, you do get EXP & Stardust for catches. It does only use Poké Balls however
-Like standard captures, it has three chances to break out. It sends a white light and vibration on each chance, followed by red if it breaks out or rainbow if it's successful, though the rainbow starts with red
-Yes, it tracks Eggs & Buddy with the game in the background
-Contrary to reports, you do get EXP & Stardust for catches. It does only use Poké Balls however
-Like standard captures, it has three chances to break out. It sends a white light and vibration on each chance, followed by red if it breaks out or rainbow if it's successful, though the rainbow starts with red