for the tesselation, you could stick to the tesselation functions in the GLU (gluNewTess() etc). It's not the best tesselator ever, but should be enough for this project. Basically (as it is the case in any font design tool) a glyph (the graphical representation of a letter) is made of contours (inner and outter contours). The orientation of the contour (the order in which you define them, clockwise or counter-clockwise) tell the tesselator if it's an inner or an outter contour (to create holes for example).
In about 1 hour you should be able to have this working properly, it's not that difficult.
And yes, looks like a very useful tool (at least for me!)
Good job!