I'll give them a listen, doubt I'll like them but they're worth a shot. Some growler bands are canny. Wintersun, Amon Amarth, Ensiferum. But I prefer clean vocals but also vocalists with range, a band without a good singer isn't necessarily a bad one but it can be a huge letdown, like Megadeth and Dream Theater for example.

Screaming, well the core metallers just take a page from the book of hardcore punk but REAL screaming, Rob Halford, Warrel Dane, Bruce Dickinson, Eric Adams and Tim Ripper Owens. Hitting some insane notes is a lot better than KSE/Bullet style.

Mind Falsetto's nothing new.

Also for style? er, "Wearing Jeans and Leather, not crackerjack clothes" a page from Manowar's Kings of Metal. Mind, Judas Priest and Saxon were doing the whole leather thing before them. (even if Rob Halford is openly gay, it all makes it kinda ironic. It was seen as the optimal peak of manliness and metal, he comes out the closet and it all gets put under the carpet like everything else out the 80's XD XD XD XD)