Is this waterproof and hypoallergic??

It’s not waterproof if it doesn’t have the 24 hours on it. I got sent the wrong ones and can’t return. Better to buy in drugstore then.

I've been using these eyeliners for many years. I wanted a liner that was waterproof but not so soft that it would smudge easily throughout the day. Depending on how fresh the stick is and the temperature of the room, it's soft enough to glide on accurately. But as it is a bit stiffer than other brands, due to its long-lasting properties, it doesn't smudge as readily. And as it begins to dry, even during application, it becomes even more resistant to manipulation. It takes some practice.

Is this liner a retractable pencil

Yes you can twist to advance or retract the liner pencil. I love this liner. Works great.

Does this stay on your waterline?

I use it on my waterline all the time. Non-irritating and goes on easy. Stays for at least the day. Might need to reapply it just a little near the ends after about 8-10 hrs but that’s not unusual for waterline. I love it!