Hiya.
Tri's only. Any quads and n-gons will be converted into tri's. UV'ing polygons (tri's, quad's or n-gons) take time no matter what. Convert your mesh to all triangles and then do your UV'ing, unless your 3d program is really on the ball and will 'port over' a tri/quad/n-gon UV'ed mesh into pure tri's, yet keep the appropriate UV map (although going from n-gon to tri's is almost certain to cause you intense, searing, polygon-pain).
Bottom line...trying to texture a 3d-mesh in WED is like trying to paint a car made out of wet paper-mache...with a broom. Do yourself a favor and do all your texturing and UV'ing elsewhere.