I am wanting to perm my hair, to get beachy waves. My hair is about 14,-16 inches long, landing almost below my chest. I henna'd it a year ago, and am wanting something like the pictures in my pinterest board. Does anyone have any tips, and advice, does a perm change hair color in any way? tell me your perm stories? Pinterest board.
I've been getting two perms a year since I was 16. Getting a perm with dyed hair will destroy it and make it really frizzy, but idk about henna. Basically you have to choose between whether you want to chemically add color to your hair or add texture. I would suggest stopping by the salon where you'd want to get the perm done and asking them as well as showing them the photos. Make sure the stylist knows what he or she is doing so the waves come out the way you want.
I get digital perms. Perms take better on thicker hair.

Pretty sure I read somewhere that if you do anything extreme to henna'd hair before its all grown/cut out, it will royally fuck up your hair. Like that shit just starts melting. Do a lot of research first.
Definitely do your research on the Henna. I'd recommend at least asking a professional, though (and find a good one who knows their stuff, not someone at Supercuts), because Henna can interact with a LOT of chemical processes. I don't know the specifics as color is more my expertise than perms, but I do work at a beauty supply and pretty much everything has some sort of warning about Henna.
As far as whether or not perming it will be damaging or not, though, depends largely on the texture, thickness, and condition of your hair as well as the products you use on it (and those you've used on it in the past). As a general rule, especially if you're doing it yourself, stay away from drugstore box kits as they tend to have a lot of harsh, unnecessary additives in them, and look instead for something tailored to your hair's specific type and needs.
If you do go to a professional, make sure you tell them everything you've done with your hair chemically in the past, even if you used box dye on it two years ago.
Alternatively, though, you could try a wave iron with a thermal setting spray, a good curl creme to enhance it, and work some wax at your roots to fluff it up a bit.
You definitely can both color and perm hair without frying it, though, as long as you're using good products on your hair. If you had both the perm and color professionally done and it still ended up super damaged and frizzy I, uh... wouldn't go to them again. Semi-Permanent dyes are non-oxidative, non-damaging, and great for chemically textured hair, though. And pretty easy to use, depending on the base color of your hair.