I think you tend to overthink things a little sometimes
Nobody can tell you which is the right setting on this particular iron. Just try it out. If the wax melts and does not smoke then you're fine. Usually that's a medium setting.
Also, most of the all temp waxes are so similar that you can pretty much go with any brand. No need to buy an expensive racing wax. You wouldn't feel any difference.
Just check youtube vids on waxing. The good ones will give you 100% of the information you need.