Sorry I cant help about wax!
But pay attention when you use the iron with wax, the base of iron should be flat without any holes in it. Otherwise the wax will get into this holes when you warm up your wax.
Hope this info will help!
Oh and yes you can use different types of irons but the best ones where you can adjust the temp preciously.
And don't ruin your mothers iron, cheap ones will do fine for waxing!