I think I'll wait for 7.0 before "editing in Photoshop."
Download the ACR 6.7 RC1 from Adobe Labs. That will process PV 2012 (but doesn't give you the UI controls). So it won't be optimal for ACR smart Objects but will render everything you set inside LR4.
So if I open as a SO in CS5 now, once CS6 is released with CR 7 will opening the smart object show the controls?
If you make a SO now with ACR 6.7 from LR4, you'll get PV 2010 in the SO. Once you get CS6 and ACR 7, reopening that SO will respect the previous settings but at that point yes, you'll be able to update the SO to 7.
At the moment it's cheaper to buy the boxed product shipped to you direct from Adobe, rather than either buying the download from Adobe or buying from Amazon. Rather odd that shipping the box is cheaper than emailing you a serial number.
2) Couldn't wait to test the Beta#2, ops! I meant, the final release
You just download the trial to use the full version. It's only a minor annoyance having to select "trial" every time you start it up until the box arrives.