I have a similar setup. Using the higher-end Kiwi BT adapter. Update rate is pretty quick.
my mounting setup basically consists of a piece of wood wrapped in dinoc with some 3m dual-lock (it's like velcro but hardcore). I have to reshape the mount a bit so that the tablet fits more flush but it's working for now.
tablet is a htc flyer. 7'' wifi tethered to my galaxy nexus (which is on a car mount for power). using tasker to automate but running into a few glitches that i need to work out.