Here we go again...
I make/have made mead both ways...they are *different*-- the actual superiority of one method (heat/boil) vs (no heat/"dump and stir") is not as gospel as I think most people tend to make it out to be. I wish people had more of an open mind about it...I'll post these links again:
Errol's boil/no boil experiment
The results of the blinded tasting
It is clear to me that heating may (and boiling certainly will) decrease the aroma, but it doesn't necessarily create inferior mead.
To answer the OP's original question (who I'm sure didn't dream there'd be so much controversy): No it is not *necessary* to heat your honey, but if you choose to, you will not "ruin" your mead. I personally don't think that Campden (sulfites) are needed for must sanitation purposes. I've not used them for that purpose, only for stabilization (along with sorbate) when I've planned to backsweeten. I think as long as you have good sanitation practices and pitch good healthy yeast quickly you will be fine (although I've waited almost 36 hrs in one case before pitching without any bad results...certainly not best practice, but it happened, and my mead wasn't "ruined.")