This one was easy, but not at all obvious. The HDMI works fine, but what I was missing was that you have to enable the Bluetooth, and that just doesn't make sense to this ol' luddite, but as soon as I did that, and closed the lid of the MB, bang. . . Right there! I have no idea why bluetooth should have to be enabled, but it doesn't matter, 'cause now I'm a happy camper! As I had suspected, I haven't seen a huge difference in anything except startup time (the trackpad is still a bit "touchy", but I'm starting to get used to it), but I haven't started working with the photo processing; that's where I'm hoping to see a HUGE increase in speed over the PC that I had been using.
Thanks, guys, for the suggestions!