I view this week's chapters almost as a 'package' deal--it's kind of hard to talk about them individually.

One thing that always, always baffles me in this part of the book is that while Elinor is (justifiably) concerned that Marianne is trying to acquit Willoughby by any possible method, does it not seem that she is doing the same for Edward? She is worried that Willoughby is "so unprincipled as to have been sporting with the affections of her sister from the first, without any design that would bear investigation." How can she not think Edward was not doing the same thing?

Yes, Lucy is unworthy of him and will make him miserable, but they were engaged and he was not free to be engaging the affection of anyone else. No, Edward didn't write Elinor a horrible and insulting letter, but these Willoughby's words from letter:

"I shall reproach myself for not having been more guarded in my professions of that esteem. That I should ever have meant more you will allow to be impossible, when you understand that my affections have been long engaged elsewhere..."

--would they not be as true for Edward? He did feel and mean more for Elinor, but he shouldn't have. Elinor feels certain that Edward loves and prefers her, but really, she has no more reason to do so than Marianne has re: Willoughby at this point.
Judging by the information we have up to this point in the story, doesn't it seem that Elinor is letting Edward off the hook rather too easily?

Does this passage from Ch. 29 make it clearer or harder to understand?

"In her earnest meditations on the contents of the letter, on the depravity of that mind which could dictate it, and, probably, on the very different mind of a very different person, who had no other connection whatever with the affair than what her heart gave him with everything that passed..."

Is she acquitting Edward because she believes he could never be so cruel as Willoughby has been in the letter, even though his actions were--for all intents and purposes--the same?