The artist is someone you know in real life and who does their art on paper, not on the computer? Then yes, every piece of art will need to be scanned, adjusted/cleaned, set to your desired size, saved as your desired file type, uploaded to your webhost, and linked to in your application.

Well what is it exactly - just pencil on paper, or ink on paper, or colored pencils, or markers, or what? Whatever it is, you will need to scan it, and if it's a messy medium like colored pencil or charcoal be sure to clean and dry the scanner between scans if necessary. And be aware that you aren't going to be able to get transparent images from a paper-based source without serious work, you're pretty much stuck with white backgrounds in simple geometric shapes (circles and ovals aren't too hard although of course rectangles are easiest.)

If the original is colored or has hatching or other fine pencil detail, it is basically impossible to digitalize it by tracing without either destroying the quality or having the artistic ability to replicate the original. Did not seem to me to be what the original post is talking about at all.

I personally sketch on paper then scan and trace - I use Inkscape to vector-ink my lines, but it accomplishes basically the same thing as people who use a tablet to bitmap-ink. But this process just doesn't do justice to a finished detailed drawing, it's intended for sketches which are only linework.

*Takes a guess at what "tracing using layers" might mean* It's possible to use layer masking to convert an image's background to transparent and clean up the outer edge so it doesn't have white/grey flecks making it look ugly. If an image is colored very simply, you can use the same process to digitally replicate color fills, texture fills, or gradients fairly easily.

Alternative interpretation, if the original has different colors of linework, you would want to trace each on it's own layer when trying to replicate it.