On another note, is it pretty much impossible to be a freelance web developer without knowing or having someone else take care of the design aspect?
There are some great resources for design, which I think can be approached by a typical programmer.
* Grid layouts such as http://960.gs/ and http://www.blueprintcss.org/
* Typogrify which helps you create better typography (and is also a resource for stuff to think about!) http://code.google.com/p/typogrify/
* Compass makes it easier to create good design with standards http://compass-style.org/
* Good read on typography http://informationarchitects.jp/the-web-is-all-about-typogra...
* Color schemes http://colorschemedesigner.com/
On your other question, yes that sounds really, really tough. You should have a few people in your circle, to work with and to bounce ideas with. I wish I had more, knowledgeable designers myself, to learn from.
What is important is having the theoretical/academic basis for all of them, because it can greatly inform your decisions about your work and let you pull from a wider swath of experience.
I don't think you should have to be a graphic designer in order to be a web developer. You probably shouldn't be (and I find myself increasingly disliking generalists). But you should understand the principles of design, and know what goes into making a graphic work, and how designers communicate and the vocabulary, just as you should know the same sort of things on the back-end for the operating system, hardware and network environment your software is deployed on.
Cheers!