how to change font sizes, and use google fonts

I’m trying to make two changes to this theme that should be fairly simple, but my CSS skills are not up to speed enough, and the CSS file for this theme is pretty intricate.

The two things I’m trying to do:

* Slightly increase the font size of the body copy
* Use a Google font for the article titles

I’m guessing the first involves the p tag, while the second involves h1 … but I’m not seeing discrete places to change these. Are there other changes I need to make to the css to accomplish this?

Thanks in advance!