W1.) What data can I share wirelessly with other Colorado users?
You can share waypoints, tracks, routes and geocaches.
W2.) How do I transfer the entire geocache including description and hint when using the wireless transfer function?
You can't. It seems Garmin/Groundspeak have limited the amount of information transfered between Colorado to just the information on the Geocache Summary page. No description or hint is transfered.
W3.) What is the Colorado's wireless technology based on? Is it Bluetooth or Wifi?
Neither. Garmin's wireless technology is not based on Bluetooth or Wifi. The wireless technology is called ANT and only supports communication with other Garmin products and sensors that use the same proprietary technology.