A mechanical keyboard is usually of a pretty good build quality and can hold up longer than a membrane. It will feel different from a membrane and most people prefer a mechanical keyboard after having tried it. As for mice it's usually not as important, a gaming mouse offers thing such as a better sensor and ergonomics that fit the hand better, depending on how you grip the mouse this can be good. You should see if you can go to a local store and try some different mice and keyboards to see what you like.