You need to crawl the faces. So say all the selected faces are quads, you would do something like this: 1. Get all 4 of the faces border edges. 2. Go through each of those edges and find which one is connected to both your current face and the new face. 3. repeat until you reach the end of the face ring, storing the faces…
yes but snap to face and surface modifier isn't as fast as polyboost and it has this ugly snap to face gizmo, that sucks, also you can't snap to face with an offset
Another way I've heard of systems interpreting mirroring is for the exporter to look at the UV face winding... so then inverted faces (facing -W) are interpreted as being mirrored.
Keywords you should look into: - Bony Landmarks of the Face - Planes of the Face - Color Zones - (Primarily a drawing thing) Measuring the Proportions of the Face - Anatomy 4 Sculptors