I have taken the express route. Heat wax bar on the iron then while hot, rub onto base.
This is actually not express route
It doesn't take much more or less time doing it this way or melting wax on iron letting it drip down. But it's certainly better way, as you have more ptex covered with wax, and less chance for direct contact between base and iron (you know, those of us who spent at least some time in xc skiing, are especially anal with these things
), so there's less chance for base to get damaged by hot iron. I always do this first, and then melt and drip wax on (or more of them if you mix waxes together and not in layers).
As far as temperature goes, 130c is quite ok general temperature for most of CH waxes, while for fluoro waxes temperature goes up even to 150c, but for racing, where every little thing matters, temperature can be normally from 120 to 140c depending on snow conditions (about +/-10c also for LH/HF which can mean also 160c in some cases). Fluoro overlays are completely different thing with temperatures up to 180 or 190c, but that's single fast pass with iron over the ski, not really relatively slow pass as with "normal" waxes.
There's few reasons why I always used higher temperatures. One... ski is exposed to heat shorter time. 20 or 30c higher temperature but quite a bit shorter time won't make heat protrude deep into ski, and influence all the glues and materials inside of ski. Having 20 or 30c less (you still need 90-100c if you want to melt wax at all) and heating ski for few minutes will sooner or later (in reality sooner) change skis characteristics (with xc it's even more obvious with even worse results). Another thing is wax itself, especially if you use high fluoro waxes. The more and the longer you heat the wax, the more fluoro goes out, and if you are paying almost 100eur/pair for wax, you certainly don't want lot of fluoro go into air, but to stay on skis making them fast. So with single fast pass, even with few degrees more, you keep more fluoro in base.