It's funny: in Dutch we have retained this distinction between controllable and uncontrollable fire with the words 'vuur' en 'brand', like in 'vuursteen' 'brandalarm'. I think that's even not so weird because they're quite different things: the former is something useful and spectacular, while the latter is a feared and devastating monster which swallows everything on its path.
According to who?
"bright (adj.) Old English bryht, by metathesis from beorht "bright; splendid; clear-sounding; beautiful; divine," from Proto-Germanic *berhta- "bright" (cognates: Old Saxon berht, Old Norse bjartr, Old High German beraht, Gothic bairhts "bright")..." It goes on, but I think you get the point.
"brand: from Old Norse brandr, from Proto-Germanic *brandaz"
Not really. It's become a fixed expression for the profession, just like sjuksköterska has become the fixed title for nurses despite it being feminine.
There are however many more examples of -man forming the title of profession, and this is not unproblematic. Thus we now prefer talesperson (spokesperson) rather than talesman (spokesman), for example.