1) Not really sure.
2) I'd say the mousepad makes me feel more comfortable while using my mousepad
3) James Training is a good idea
As an addition if you're using mouse, disable mouse acceleration (Windows control panel > mouse > uncheck increase pointer precission) then adjust sensitivity to whatever you feel better with (do this on osu! as well since it's more precise)
2) I'd say the mousepad makes me feel more comfortable while using my mousepad
3) James Training is a good idea
As an addition if you're using mouse, disable mouse acceleration (Windows control panel > mouse > uncheck increase pointer precission) then adjust sensitivity to whatever you feel better with (do this on osu! as well since it's more precise)