Resolution affects FPS because a higher resolution means more pixels for the graphics card to have to render, which is harder to do. More is harder. Harder means FPS drops.
Refresh rate does not affect FPS in any appreciable way. FPS affects screen tearing though if the FPS is not consistent with the refresh rate. Optimally you would want exactly 144FPS if you had a 144hz monitor. Without Gsync or Freesync though, that is not going to happen very often if at all. But getting as close as possible will usually offer an improved situation and having Gsync or Freesync should mostly eliminate it entirely.
Obviously, it is more complex than just that but that is the gist of it.
Playing with a graphics card that is capable enough for 4k...