RE: free CAD
I've only been drawing in CAD since last Spring - although I've been using Photoshop professionally as a designer for the last seven years. Of all the programs I've tried, Deltacad is hands-down the easiest to learn, especially if everything you know is raster/pixel graphics.
It's a big jump from drawing with pixels to drawing vector lines. Not many skills and techniques carry over, so you are basically learning how to draw all over again. I still find myself trying to do things in cad that can only be done with pixels, it can be frustrating at times when you are so rooted in one way of thinking. I'm sure people who started out with vector drawing would encounter the same stumbling blocks if they decided to start using Photoshop. They are two totally different worlds with little overlap.
Deltacad makes this transition easier than the other programs I've tried. If you started out in cad - not raster - then I'm sure your opinion of Deltacad will be different. But, coming from my side of the fence - with a brain that is wired for pixels - it is the most intuitive program to use.
As for using Deltacad, here are four plans I've done with it. They are not finished products, but I can easily use them to build from.