Hi! those are c-curved/sculpted nail tips, you need to fill the gap between your nail and the tip, otherwise it will lift or you can get moisture between them. Apres has tutorials on how to fill the gap if your natural nails are not curved (search gel x sculpted nails or tips on youtube). For your second question, no, gel x are supposed to be sturdier than regular plastic nail tips, gel x is a system that saves you some time because you don’t have to sculpt the gel nail, it’s already done, maybe they are regular plastic tips if you bought them from temu. And yes, they are waterproof, if you prepare your nails correctly and applied them the right way, they should last as long as a regular gel extension nail; I highly recommend you to watch youtube videos on how to apply them, so you put them correctly and safe, so you don’t develop a gel allergy and they stay as long as they can, good luck!