Q. If I use Xbox One streaming to Windows 10 can I perform a different activity on the Xbox from the streaming user?

Q. If I use Xbox One streaming to Windows 10 can I perform a different activity on the Xbox from the streaming user?

A. No. while the Xbox One is streaming to Windows 10 the local Xbox One console will be "in use". If a game supports local multi-player then it would be possible for a person at the console to sign-in and play the game with the person who is connected via streaming.