Regarding Fanny's character development, the example you give are not character development. They are examples of story development based upon a fixed character interacting with new situations. Does Fanny actually change as a character in any of those situations? Do her ideas about life, the world or the good alter from what they were before? No. What happens is that the plot advances and in each situation, Fanny clings to what she knows to be right and the situation flows around her. She alters the cast, but is unaltered by it. She encounters Mary Crawford, discerns her character, and is proven correct. She mentors Susan, but this is not a development of character, but merely an assumption of role (just as her marriage to Edmund is a change of role rather than a change of character). Austen uses the entire Portsmouth event (along with her rejection of Mr. Crawford) to demonstrate just how steadfast Fanny is. Sir Thomas and Edmund are both mistaken in thinking that the Portsmouth visit will change Fanny's mind because her character is already fully formed.

Contrast that with Edmund. Edmund thinks he knows the good, he thinks he can discern character and he thinks he knows what he wants; in each case he learns that he is mistaken. He is a different, wiser, and humbler person at the end of the novel as a result of self-discovery. Fanny is the same as she was before--just better situated.

Also, I did not write that Edmund was a bad person--just that he did not deserve her. The religious context is media via establishment Anglicanism--not American Great Awakening, total depravity, Jonathan Edwards' Sinners in the hand of an angry God Protestantism.

Regarding ordination, it is nevertheless a fact that Austen wrote to her sister the she was going to write about ordination. On the one hand, one could say that Austen was writing ironic nonsense in her letter, but because she was contrasting this "ordination" topic with Pride and Prejudice, the only really reasonable explanation is that we was referring to Mansfield Park. No other Austen novel comes close to a contrast to the former and the only other Austen novel that has the taking of religious orders as a plot point is Sense and Sensibility, which pre-dates Pride and Prejudice. Certainly, one could also read Mansfield Park as a "correction" of Lovers Vows just as Northanger Abbey is a parody of the gothic romance novel, but I submit that what we have here is a both/and rather than an either/or situation. Austen's very conventional religious sensibilities are most prominently displayed in Mansfield Park (as compared to her other work), and therefore it simply makes sense to take her at her word and accept ordination as a hermeneutic tool when reading the novel.

Besides, even if one wants to dismiss the theme of ordination in particular, it would be folly to read Mansfield Park without considering Regency-era Anglicanism. The role of the clergy in society is clearly a theme in the novel, and it must be remembered that the Church of England with undergoing quite a revival at the time. It simply must be considered. To neglect this aspect of the novel would be like trying to read Book 6 of The Brothers Karamazov (or anything by Dostoevsky for that matter) without any thought whatsoever to the author's Russian Orthodoxy or his relationship to Elder Ambrose of Optima. One need not import Anglican sacramental theology into Mansfield Park to appreciate the religious themes in the novel, but to ignore the Anglicanism in the novel will hinder a full appreciation of Mansfield Park.