My friend, I'd hold off on adding more things until you know what xenia need, what a button polyp looks like, etc. It's really exciting to add new things, but it's also a horrible feeling when you lose them, and find out its because you didn't realize what the needed. Go slow, and do lots of research. I say this from experience. Have you ever looked at the wet wed media website? They have an incredible amount of info there! Good luck with your tank!
ps we have that same kind of xenia in our tank. It's red sea pom pom xenia. Watch it, becuase it can spread like crazy!!