Hi Dan. I think you're almost there, but rather than focus on a niche feature, you should probably focus on a niche audience. You can do this for example by setting your game in a particular village or making the game about a particular hobby or niche group activity. I'm convinced that this is the key to being a successful indie. See more details in my blog post how indie developers market their games.
There's two easy ways to do it, or a combination of the two:
Buy a small (A4/letter or A3) drawing board or parallel ruler (one with a roller in it). Draw the front view, then use a mechanical pencil and draw feint horizontal lines at each relevant point - e.g. top of head, bottom of chin, middle of mouth, middle of eyes etc. Then draw the side view making sure each respective point lines up.
Draw both front and side view by eye. Scan and import into GIMP or Photoshop. Create rulers/construction-lines as before, and use the various tools to stretch parts of the side view to fit the front view.
I echo Dave's advice that you should probably consider using a different person for the tiles/backgounds vs the sprites. It can be quite a different skillset, and you would probably get the best price that way.
Secondly, I recommend writing up a detailed spec so that artists know what they're quoting for, and everyone knows what the deliverables are. Once you have this document you could send it out to a range of artists and go for the best quote.