Your final "btw" paragraph has me saying no, do not do the 140 for the course. Seriously, if it would be that much of a financial hit, and you can barely get the motivation to pick up a pencil - you're setting yourself up for even more disappointment in yourself compounded w/ the financial hit. There's plenty of free stuff, I'd do that if I were you, until when and if your btw turns around. I have motivation/adhd probs as well, and telling myself "If i spend money on this it will MAKE me do it". Nothing could be further from the truth. In fact, quite the opposite. Mess around w/ free stuff, and if you feel the inspiration buy yourself an xmas present of the course

Yes. The process will depend on the tool, I'm really familiar with photoshop. Essentially you scan the image and your can isolate the line art to its own layer. That way you can color on other layers without worrying about covering over your line art. Plenty of tutorials on youtube on how to do this.