For (a) I would recommend Mark Boulton's book, Designing for the Web, which is available free online:

http://designingfortheweb.co.uk/book/index.php

It has really competent sections dedicated to aesthetics: typography, color, and layout. That he made it free is unbelievable. It's a resource I always recommend to the developers I work with (I'm a designer) who want to understand more about design.