I believe the PRO-HD outputs 720p/1080i on the HD connection (component cable). It does NOT output 1080p; it doesn't even have an HDMI connection, just component.
Only ONE client can watch the output stream at any given time
There is a client for the iPhone; I believe the client for Android is currently in development and will be out soon
I can't answer the other questions, but hopefully someone else will jump in and give you more.