Your comments about v and VII make a lot of sense to me, and I shall think about what you've said. I personally love the sound of harmony based on the natural minor (Aeolian) but I see what you mean about the possibility of the tonic being ambiguous if other keys are tonicized before a true dominant in the original key appears. I shall think about this in my next exercises.
Your point about the augmented second is a good one, Iit wasn't intentional, and now - when listening for it - I do detect a slight 'awkwardness' and shall avoid this interval in future
