I’m sorry to say that the EyeX Controller currently does not support more than one controller. We do however listen to feature requests so things may change in the future.
Regarding your question 1. There is today no good way of synchronizing more than one EyeX Controller. Unless they target different areas this will result in interference and noise and is not recommended. How large is the screen you want to cover at what distance is the user expected to be from it?