It has two outcomes, hence is a d2

No, dN means there are N different outcomes. Does not matter if they are flat or anything. Cube with two of each number from 1 to 3 is a d3.

Name one with purpose, then. There is the big cave with the boss. It is separated in two halves by a long ass platform. There are no enemies, exploration, rewards or challenges on the platform. The sole purpose of it is to make you run right and then left, instead of just facing the boss right away.

It is slightly worse then HK.

Yes, it is positive, and power 1/2 is, too. Two solutions emerge from solving equations, even primitive ones, like x^2 = C.