Definitely go get some professional advice on how to care for your voice. It's a lot more precious than the music, as heretical as that may sound. To all who equate screaming with fire and passion, remember what that Jimmi Hendrix said (and I paraphrase). It's what is behind the notes that counts.
I believe it was Tonny Di'anno who had to leave Maiden because he nearly lost his voice.
As for singing techniques, Middle-Eastern music is worth investigating, into how the singers project their voices.