I don't think there is anything wrong with wanting music you like at your own wedding, and its really unclear if he is saying he wants only death metal, or if he wants some just mixed in. I do think its an odd choice for a wedding reception but who knows, maybe all his guests love that kind of music too and he wants them to enjoy the party.
I don't know any of the back story about the dress, it may not be common for a groom to care but I don't get the whole "he's so controlling" comments. There are plenty of brides that want their grooms to dress a certain way on the wedding day, and that is totally acceptable?
OP, if it really bothers you maybe just sit down with them and explain that you don't think that type of music is appropriate for a wedding. Have you talked to them about it, or are you just assuming that there is no room for compromise?