as i understand your question, and please correct me if i'm wrong, the vi (aeolian) mode would have stable tones on its tonic triad A C E, and G would be less stable as the seventh the the tonic triad Am. in other words, although the use of harmonic minor may strengthen a resolution to vi (Am) it is not necessary to do so.
much depends upon context, as i would imagine you suspect, but the tonic triad of the mode in question is the primary source of stability in modal situations. so the answer to your first question:
"1. Playing in (vi mode), the chord tones are ACEG and as I understand, (A) is still an active tone and CEG are still the stable tones. Is this correct?"
would be no. think about it: why would "A" not be stable during the sounding of the sixth mode's tonic triad Am...
please ask further if you need. the subject of "modality" may lead to disagreements but i don't think in this case it will be so.
edit; ignore the following if it makes any answers to your question more hazy
tonic triad C E G (most stable)
subdominant triad F A C (less stable)
C, as an element of both the subdominant and tonic triads, is generally stable; therefore, the active tones are F and A...
dominant triad G B D (most unstable)
G, as an element of both the dominant and tonic triads, is generally stable; therefore, the active tones are B and D. further, F is an element of G7 (V7) as well as the subdominant triad F major and may be considered most (active) dissonant along with the leading tone B.
from this, you may imply that any tones not found in the tonic triad are active or otherwise unstable.
tonic triad A C E (most stable)
subdominant triad D F A (less stable)
A, as an element of both the subdominant and tonic triads, is generally stable; therefore, the active tones are D and F...
dominant triad E G B (most unstable) and its truly dominant cousin E major or E7 (E G# B and D)
E, as an element of both the dominant and tonic triads, is generally stable; therefore, the active tones are G and B and especially G# as the leading tone...
your example was in Am, so perhaps your confusion may be related to the G# itself as standing apart from the G natural found in the pure minor mode. this may be a bigger subject than you anticipated (to sharp or not to sharp the seventh G) but i for one have absolutely no trouble hearing the resolution from the subtonic G to the tonic triad's A.
as i said, ignore that last part if it's not helping but for me, an inspection of the basic I, IV, and V chords has been most useful in learning how to "hear" these things.