As I already stated, these questions are quite difficult to answer directly, as I'm more or less a plain citizen with just a better historical education than most Germans
I have no studies or even just polls at hand so bear with me - it's just a personal view
For the average German, the 3rd Reich is incredibly far away. Yes, almost all of us had learned about it in school (though in varying quality), and as a German you are still very much exposed to a huge public remembrance culture - each anniversary like the Machtergreifung or the liberation of Auschwitz spawns a lot of public speeches, commemorative ceremonies especially on higher levels (like Bundestag), articles in newspapers and magazines and many features on television.
But I really doubt John Doe is really caring very much about it anymore and I don't think that had been much different 10-15 years ago. 20-30 years ago that could have been a different matter, but it's hard to tell for someone not being 40 yet
It is however very present in all higher levels/circles, media, politics, humanities etc. It is very much influenzing modern politics and semantics. The things that have (or may have) changend in the modern perception of the 3rd Reich and nazism are somewhat limited to academic circles, high quality medias and people actually interested in that topic.
One of those things that have defenitely changed is the view on the Wehrmacht itself. 30 years ago there may have been a commomon consensus that the Wehrmacht had been (forgive me this simplification) "innocent" - more a victim of Hitler and his evil minions himself than a active player in expansion, extermination, war crimes. This has definitely changed, being replaced with a much more differentiated view.
But again, this is more an academic/media phenomenom. I'd say: For the average German, such things don't really play a role anymore.
And I doubt there is an increasing number of youth being attracted for the myth. Actually, over the years I have come to the conclusion that the
myth is much more present in countries like the United States or Great Britain with a totally different culture and differrent (=much less) taboos (and laws!) on that matter.
"I have the sense that the average German citizen blames the Nazi hierarchy for the events that took place, are any of them blameless in the populaces eyes (ie Speer or Donitz)?"
I'd say most Germans would not be able to tell you who Dönitz was
Despite the rememberance culture I mentioned, these are academic debates & topics these days.
"Are some individual military units (either German or some other nation) vilified by the populace in Germany?"
The general public view has changed on the Wehrmacht, but discussions about individual units are, again, pretty much academic ones