Are hair straighteners harmful? Whats the difference between perm and creatine?

my hair is curly..the curls are really tight so its kinda short..and i want it longer so i decided to braid it ..i keep braiding it but its not efficient ..so i want natural none harmful ways to make my hair weavy.. ive been told that hair straighteners cause fast hair loss and makes hair white sooner and ive also been told that perm hair is really dangerous since its chemical and same goes to creatine.. i would also like to know the difference between perm and creatine and how i could straighten my hair without it being harmed?