Hmm.. whenever I was working on stuff to be printed (keep in mind this was 5 years ago - i don't know any standards now) 100 dpi was good for a general color print, 300 dpi was good for a high quality print and continued editing. might wait for another opinion or two besides mine though, or search the forum. and inkscape should be fine, i just don't know if inkscape has a feature similar to the live trace feature (I'm lazy, so I preferred the route that had the machine doing as much work as possible) although learning how to do vector linework is a good practice in itself - when I tutored in illustrator one of the first exercises we had them do before starting their own projects were learning how to manipulate the bezier curves, and then value differentiation/mapping of grayscale images, to better their ability to distinguish and identify lighting/shading differences. We would actually use an old grey-scale image of bezier himself.