Yes, it does affect the corners. You always have both even or both odd numbers of corners and edges. Say there are 8 edges and 10 corners. If you do 8 times T perm, the corners are still solved. If you have 9 edges and 11 corners, then you do parity alg.So I am wanting to learn how to solve the 3x3 blindfolded, and I have been looking on Jperm's website, and when swapping 2 edges with the t-perm I noticed it also affects the corners, and when you do setup moves it would move those edges around, so I was wondering if that actually affects the solve and memorizing the cube.
There are no algorithms that only swap 2 pieces. That's only possible on a even numbered cube starting from 4x4.
And yes, setup moves do affect the edges. That's why you undo setup moves.