i say Adobe products work better in unison. (commonsense that products from the same company are more adapted to work with each other)
meaning, Illustrator and Photoshop work better in tandem rather than Coreldraw and Photoshop or some other mix.
i use Illustrator and Photoshop at work and the interface is nearly the same, so you'd have less time to get confused when working to and fro.
How i colored the VFII girl:
1.scan
2.cleanup the lineart
3.make color layers (i set my layers to Multiply) using the selection tools to specify particular areas with the same color
4.use the paintbucket tool to fill in the selected areas
5.after completing the entire color scheme, i use the Burn tool to make shades and shadows
6. to recreate that dotted coloring, use the Halftone filter on your color layers.
7.and then post your finished art for your friends to enjoy.
finally, as the names suggest, Adobe Illustrator is for creating vector image illustrations, and Adobe Photoshop is for editing (cropping, coloring, re-coloring etc) existing images (like pictures, or the artwork youve made in Illustrator)