I was 50/50 between indented and no line space, and indented with a 2-3 pixel space. I finally clicked no pixels, but only because I already use the extra line spacing setting on my Kindle, and adding any extra looks too much.
If I didn't already space them so wide, I'd want the extra pixels.
I also like indents to be small - 0.5 em is my favorite.
For section breaks, I'm happy with * * * (and there should be nothing less, imo) but I always appreciate and enjoy the extra effort of a nice little graphic instead, especially if it's thematic in style.