Well, now that I've had the Iconia for a few days, some updates and comments:
Not charging from USB is pretty standard for tablets. You just don't get enough current from a USB port or even a plug-in adapter to charge a tablet in a reasonable amount of time, so they use small 12V (or 18V or whatever) supplies instead.
I finally got the GPS to work. It was just taking its sweet time to do a cold start I guess, because once I tried it again outside at home it finally locked on after a couple of minutes of running GPSTest. I think perhaps I have been spoiled by how fast the GPS locks on my phone when it's connected to the mobile network, but at least my Iconia isn't defective.
Contrary to some of the rumors, the wifi-only Iconia does not have a secret 3G modem in it. The SIM slot is just an empty hole. Presumably there will be a 3G version at some point.
Thanks for the pointer to Android File Transfer. It doesn't seem to like my Mac at all, but it turns out Dropbox or a USB stick are just as easy
I agree that the screen depth could be an issue for some applications. Definitely worth thinking about if you're likely to notice the difference.
Things move fast in the Android hacking community -- since I posted my first message the Iconia has been rooted. Haven't done it myself yet though.
--Rob