Will using the ControlBlock to power the pi affect my ability to overclock? Will it affect my ability to power controllers/mouse/keyboard/thumb drive/wifi from the USB?
The MOSFET that the ControlBlock uses is the IRLML6402 (http://www.irf.com/product-info/datasheets/data/irlml6402.pdf). It is rated for a maximum of 3.7 A.
The ControlBlock works with the various overclocking configurations that can be selected from within the rasps-config tool.
If your other USB devices work well is hard to say for me since that depends on their power consumption behavior.