I also use a travel iron - they are cheap, more easily maneuvered, and they don't tend to get too hot as they are cheaply made!
and yeah, once the wax is smoking then it's too hot - turn off the iron and open a window if this happens as those fumes can be toxic! the wax will burn well before your bases so you shouldn't have issues with damaging them.
i tend to wax my own but if the skis need serious attention there is a place on rodney street in edinburgh who just did mine and fixed them up proper. i had some deep gouges right through to the metal after hitting several rocks going down a wind scoured off piste bit in between val d'isere and tignes when i was on holiday a couple weeks ago. i nearly cried when i saw the bases after that - but now they are totally sorted. he fixed them with p-tex and glue wire, gave them an excellent waxing which apparently was finished with a horsehair brush - for 20 sheets.
the guy in the shop was a great bloke as well, very knowledgeable and tried to turn away my business as he said i could do it myself but i didn't trust myself to fix such serious damage with my first go at p-texing.
i don't think they have their own website but here is their entry on gumtree: