Thanks for the feedback so far guys. I'll probably try both helmet and on bike mounts, though I'm not sure I want to stick a mount on the plastic body with the hopes of removing it later and not damaging the finish. So maybe I start with the helmet, and a less visible place on the bike.
As for power, I used it some in my car and hiking, and got down to 2 (from 3) bars pretty quick (under 2 hours). Since it has a built in screen (which stays on for a while then goes out) it eats more battery than the older ones. And I hear the WiFi (to remote or cell to control it) will eat even more I've already bought the spares and they'll be nice to have. I plan to have some form of power on most bikes, but their primary purpse will be to run the GPS, so an extra battery could come in handy for the unit. (I plan to use power sources that allow me to plug in most any USB capable device to charge, phone, GPS, camera, backup battery pack, etc.)
My Tablet (an ASUS MeMO pad) has 32GB HD, so it will provide some space to offload stuff. I can also attach a USB, so I could carry an external HD and offload to that too. Of course I'm still learning how I can find info on what the tablet storage capacity is (how much is used vs. free, a simple thing in windows seems not built into the Android OS). More cards are definitely in the works, agree the largest possible is best. I want to ride for a few hours and see just how much of the card I eat up with constant video. So far I've been impressed letting it run for 10 minutes or so, click the shutter (to finish and save the video file) and it doesn't have a long delay (must be writing a file as it goes, there's no where to buffer it).