There really is no need or benefit to reading a memory card through the camera other than avoiding cluttering your hard drive. If anything, you're just going to slow yourself down. Basically the camera just acts as a really expensive card reader.
I typically work with two memory cards. As one gets close to being full, I look for a natural break and swap the cards. Stick the full one in the card reader and let ACDSee suck off all the files while I keep shooting.
When you're printing you're typically looking for 250-300 ppi. Typically your printer is the limiting factor here, though. The calculation is pretty easy after that. If you want a 10" wide print at 300 ppi, then you need it to be at least 3000 pixels wide.
A RAW image is just that, a raw image. It's basically the un-altered data from your camera's sensor. Typically in any other format, your camera will adjust various aspects of you image to make it look good. RAW is very powerful but a royal pain at the same time. I usually use it in situations like mixed light sources, to get the white balance right. This covers some of the details better;
http://en.wikipedia.org/wiki/Raw_image