New Surface Pro owner, couple questions for the "pros."

Just grabbed that crazy $599 Best Buy deal for the 128GB on a whim. I'd been using the Dell V8P, which I'll likely be selling on now, so I feel I've largely got the hang of W8.1, but there are a couple things with it that are still nagging at me, and I've also got a couple of questions about the Surface Pro in particular.

First up: does anyone know of a way I could configure the Windows button to toggle between not only the Start screen & the latest open app, but also throw the Desktop into the mix there, so it toggles between those three? I'd really like to get the Desktop "app" off my start menu, but I need it frequently enough that I can't afford to without a simple shortcut.

Second, and this one's a bit more obscure: I'm currently using a USB 3.0 DisplayLink adapter to connect to two additional monitors. I know this thing has a MiniDP connector on it, but the MiniDP-HDMI adapter I purchased doesn't seem to be working, and neither does my 27" Apple Cinema Display. For those who know, do you reckon the USB 3 DL adapters are, as they say, "close enough for government work"? I don't intend to do any gaming beyond solitaire on these external displays any time soon, just FYI. Flash video seems to be working fine at the moment as well, and the less cables I have to connect this thing to when I get home, the better.

Third, does anyone have experience with a decent, _compact_ portable charger for this thing? I've seen a lot of options online, but many of them get pretty terrible reviews. OTOH, I'd like to be able to leave my main charger at home, and not have such a bulky one in my rather small (by design) messenger bag.

Finally, what would be the best way to go if I want to manage downloads between my iMac and Surface Pro with space being a concern on the latter but not the former? Is there any way to mount an external ExFAT drive to both machines at once, or at least to switch quickly between which machine it's mounted to?