These words aren't German borrowings, so that isn't related at all. The ae in this class of words is from Latin æ (ultimately from Greek αι). The ae->e shift was an attempt at spelling simplification, to remove some vestigial Latinisms, but only partially succeeded.
True, although I believe than in itself is only a slightly older (circa 1900) spelling reform. In older German books, you see Aesthetik/aesthetische/etc. instead. Lots of borrowing and adaptation...