Yes but if no restrictions take place, that axis will be in the 4th dimension. (If this seems uninuitive then compare it to 2D rotation; the rotation in xy-plane happens around the z-axis, the 3rd dimension). There's also the possibility of finding the transformation matrix for the corresponding rotation.

Now if you already have the 2 values for rotation, then what were those values representing? The rotation that happened in the w-dimension? Or perhaps they were numbers for one of the x, y or z axises? I those were the cases then... they happened around the axises where those values came from.

Could you elaborate a little on where these numbers come from and how they will be used.

Speed of rotation is simply the speed at how many full rotations (2 pi) happen per unit of time.

rotation_speed = rotation_amount / 2*PI / rotation_time