By Monday??

oohh.. I wonder if that'll be enough time.. Anyway, let's look on the bright side: (I'll tell you what I use and hopefully it'll give you some insight)
1. I use Corel Painter 8 (mostly for coloring in) & Photoshop Elements (for touching up).. both programs are expensive, (I only have the trial version of Corel Painter which you can download of the net) and I got Photoshop for free with some software.
2. I preferably scan my images that I have drawn, because it's time consuming to draw them on the computer if you're not a pro. And I'm certainly not a pro, so scan away to save time.
3. Use a tablet to color your things in, it'll be like drawing on paper and much easier than a mouse. I use a Genius tablet. Wacom tablets are the best though but reeaallyy expensive.
4. I open the scanned images with Corel Painter, and "paint" the scanned image, there are tons of brushes that you use. I tend to use the 'Oils: Fine Camel brush' and blend the colours together with the 'Tinting: Diffuser or Softener'. Use 'layers' to paint your image, because if you don't like something, you can just delete that layer. Save the picture as a jpeg. image (it's the most common one) and make sure the settings are on excellent so your picture doesn't turn out looking grainy.
I hope some of this made sense to you, coz I know it must all be very confusing. I hope I was of some help. Just an example: Below is a picture I drew and scanned, colored on corel painter. It took about 5 hours (I try to be a perfectionist) but you can always rush to get your collection done by Monday. Good luck!