[Adding a Digital Multimeter LCD to XP-720]

Hi,

I want to add to my power supply which is 0 - 20 V+/- @ 1 A and +5V @ 3A a LCD DMM.  I want to use a 9V battery due the load of the LCD will be independent of the circuit.

So I made a search. I want to make the following circuit:

It is capable of switch between each output and to measure the output current. The problem is that I am having difficulties understanding the circuit shown.

I don't understand what is the I-Sense resistor, and the "To +Vout Via Main board" outputs. Do I need to connect this directly to the cable that goes out from the PCB right?

In addition he was talking about: "There are no RF decoupling capacitors in the circuit". Then he added some capacitors, for what this is benefit?

Source: http://www.io.com/~n5fc/xp720.htm

[Power Supply 0-30V]

I just wanted to turn on a laptop which use aprox. 19.5 V and 3.42 A. Then if 10 A is too high what if I want 5 A?

[Power Supply 0-30V]

I want to know what I need to do if I want 0 - 10 A output instead of the 0 - 3 A.