Well i appreciate your trying to learn Turkish but ... it is one of the most difficult languages in the world...
>Because you have to memorise many suffixes and their rules... and many grammar rules that might not make sense to you your whole life.
Also you have to learn many expressions special to turkish... but u will probably have less difficulty in prononciation...
Unfortunately i have to tell that there is not any turkish groups like metallica or dream theater..
But i tell some of their names so u may listen to them:
-Pentagram (quite heavy)
-Haluk levent (this guy is not a permanent member of a grup.
-Şebnem Ferah (a woman with a nice voice)
-Bulutsuzluk Özlemi (nice group except for vocal)
-Kurban (not very active nowadays)