You have 256 points for changing fueling and 256 for ignition. (16x16 maps) It also has two outputs for driving extra injectors, as well as changing the Vtech point (if your cars have that) Other things it can do is allow you to change airflow meters, fit larger injectors. You can fit a wideband lambda sensor to it and have it map your car to specific AFR values. It allows you fit turbo, and in most respects you can do anything with it other than increase the factory RPM limit.
There is an option on the side of the E-manange, that allows you to change the fueling yourself in as you say 5 points by +-20% you dont need anything else (software wise) to do this. however lambda feedback is as always vital.
Ed