This honestly sounds like hardware failure. Bluetooth is very stable for me with a Magic Mouse. Your USB and HDMI issues seem related. I'd wager a power issue.

This honestly sounds like hardware failure. Bluetooth is very stable for me with a Magic Mouse. Your USB and HDMI issues seem related. I'd wager a power issue. Make the problem reproducible and they'll swap it over at the Genius Bar, who are extremely helpful if you're polite to them.