Not sure about MCTB but TMI was written after this and is a well regarded secular resource https://deconstructingyourself.com/best-meditation-books-201...

Both. He's an over-the-top modernist, but did quite a bit of practice in Burma with Buddhist monks there.

It's definitely using buddhist framework, but he's an empiricist to the bone. Mandatory SSC review: https://slatestarcodex.com/2017/09/18/book-review-mastering-...