Excerpt advice needed

I need to tweak the automatic (non-explicit) excerpt generation in two ways:

1- change the number of words used
2- prevent the stripping of HTML tags

I’ve been looking through the code, but I can’t quite find the files I would need to edit to make it happen.

I’ve seen answers to similar questions before, but they’re applicable to previous versions and don’t work with the newest (2.0.3) which I am using.