On December 21st, 2015 on the Orbcomm OG2 mission, Falcon 9's first stage landed 6 miles from its launchpad.
What was the highest altitude reached by the first stage, and how far did it go from the launchpad?
The first part of this answer is data provided by a reasonably high fidelity simulation of the launch. While not perfect, it is the best data that anyone outside of SpaceX has at this point. More information can be found here.
At its highest point, stage one was just above 180 km. At its farthest point, it was ~95 km downrange. Again, this data isn't perfect, but we can hopefully expect SpaceX to release more information in the coming days and weeks.
As far as velocity goes, at MECO, the vehicle is traveling at around 6000 km/h, or mach 4.87. This data comes from direct vehicle telemetry that was displayed on the webcast.