EASY ANSWER: Pinch and Zoom is a capability of the Capacitive Screen and is not natively available on the S7 resistive screen.
LONGER ANSWER: 1. Technically possible to do this on a resistive screen, it has been shown on other devices but the necessary code has not been tested extensively at all, and it is not very good. 2. There are now TWO variants of the S7, a capacitive screen model that is on sale in Europe and possibly Asia at the moment, and the resistive screen model which is the $299 version at Best Buy. It looks like if you could get the capacitive screen version in the US, it would run at least $75 more than the current model.
Overclocking is basically overriding the system setting that control CPU in order to "speed" it up. This does speed up the overall system, but YMMV. There are apps available that will allow you to do it without being rooted by getting root for the app only.