How does Gynecia appear foolish throughout the reading? Note pp 912, 914, 915. How does Basilius appear foolish? (Pp 915, 916) and reader's knowledge that the "woman" he pursues is a man and young enough to be his son.

In Astrophil and Stella, therefore, we would expect that if Astrophil is pursuing an illicit love, there would be some comedy. While there apparently is not, and perhaps the matter really is too close to Sidney's own grief for Penelope Devereux Rich to be comedic, the poem still insists on the folly of the love. (Another way of reading it would be to see it as a mockery of Petrarchan conventions. Much of it focusses on writing and reading poetry. The reading given here allows us to see how Sidney's poetic theory might be applied to Sidney's poetry.)
In fact, the whole sequence seems to revolve around the contention between reason (right judgement, conscience, wit) and desire (will to motion)- arguably a Pauline trope [that which I would, I do not and that which I would not, that I do]. This is repeatedly expressed in the lover's knowledge of Virtue and his lust [Desire] for a phusical relation for Stella which she refuses because of her chastity.
The trope of Eternal love in the final sonnet in the text (not a part of the sonnet sequence before which it was written) seems to express in terms of virtue, a resolution to the sequence which in itself has none. This trope is derived from Castiglione--the final part of the Courtier presented in your book.
See sonnets 1, 5, 10, 45, 52-53, 69, Fourth song and "Leave Me." For an arguably problematic poem (it can be read hyperbolically) see "The Nightingale."