I would wait for the supersonic rather than get the hero.
Multi-tasking is just as nice if not better on Android when dealing with the web browser (the pre's browser has to reload the page when you go back to it).
There is no touchstone type thing. There's a mat with a univeral plug like thing that can do conduction charging... but you still have a plug which means its pointless. I miss the touchstone, but I got an innodock jr and now I don't miss the touchstone anymore. It can charge AND sync to pc (not possible on the touchstone). they are compatible with larger batteries unlike the touchstone (im using a 3500mAh battery). And its cheaper for each unit (with usb cable) than 1 touchstone without cable.
Youmail= available in the market... BUT visual voicemail is built into the Sense UI (works great, had google voice when gdial pro still worked on the pre). The google voice app works fine, but force close every reboot for me, not much of a problem, but a stupid pop-up came on the screen every time, and the stock VVM client works fine, so I ditched google voice for now.
EDIT: There is a DirecTV app now.
Hope I answered you're questions. I Have a Hero, I love it much more than a Pre, but I will probably get a Supersonic when it comes out. I went through 5 pre's for hardware issues so I was able to switch at no cost to me, which made me happy. I'd be glad to help you out with any other android ?'s I can answer.
Advantages of Android:
No patching for most things available from Patching WebOS. Even a tethering option is available in the market for free. If you root, you can do wifi tethering.
Themes, although I'm in love with Sense UI, you can add a home replacement and install themes without rooting.
Widgets are friggin awesome, 'nough said on that.
Honestly, the only advantages of rooting would be to try out other ROM's and take advantage of some root only apps in the market. Its not necessary in order to have a good experience on the device. The supersonic should feel much faster than the Hero, and will probably have other goodies to boot. 4G isn't going to be a selling point for me as no cities in Florida are on the list for being added yet, but if you are located in one of those lucky cities, then I would definitely wait for the SS.