Hey,

Do I need to keep then for crafting ?

for the dragon suit yes u will need them. at 100 smithing skill

Not really, there are plenty to be had from random encounters and dragon peaks.

Sell it all. You only really use them toward the end of the game- when you've leveled up your smithing enough to be able to craft them- and you run into enough dragons that you'll be able to get enough scales and bones if you start collecting them only once you can craft daedric items.

Thanks....

If you're going for light armor then keeping some dragons scales might be handy but you don't need to may (about a dozen of so), given how Deadric is better then Dragonbone, the choice of going for Dragonbone armor is literally only preference but it's easy to get both to hit the armor cap anyway.

Don't bother unless you really like the look of the armor. Daedric is better, and doesn't waste a perk.

If you plan on making the armor at 100 smithing, while also using the perk, then yes, they are worth keeping. You can sell them alone if you want, but you can also craft the armor and get more for your money, but it's totally up to you.

Technically, Dragon Armor is the best for both types. If you improve Dragonbone, it easily breaches the Armor Cap, and weighs less than Daedric, making it superior. Dragonscale is just all around better than any other Light Armor, as far as AR goes.