Seeing I'm using 3.4 SDK (qhich references support for Retina Display), and Flash CS6, and also the 'High' publish setting, can my app be 'offically' referred to as a HD Retina Display app?
The main reason I'm asking is because my Flash stage is only at 1024x768, so I'm wondering if it has to be set at 2048x etc
If there's an official Apple definition of an app being a "HD Retina Display App," then I don't know the answer. But, if your app plays on iPad3 Retinas, then in my opinion (not worth much), I'd say "yes" -- it's a HD Retina Display App (especially if you're getting the decent high-res imagery you stated).
Regarding the "jaggies" on the vector images, I have the same problem. I think it's an AIR issue. For my client, I had to convince them to just accept it, which they did (thankfully). To try eliminating the "jaggie" issue, I used PNG files in some cases. But, those resulted in "fuzzy" appearances, which isn't much better.
You might want to update your AIR to 3.7 SDK and publish with that, as it's the most-recent and fixes a few older issues.
Please advise when you go to submit your app to Apple, because Apple rejected my app for problems on the iPad3 Retina (see http://forums.adobe.com/message/5414458#5414458 ).