Need Suggestion on Selections for my first project

Hello LCNC Community..!

Today i am feeling glad to say that i have got my first real project to work on integrating Linuxcnc over Commercial CNC controller on a 3 Axis Milling Machine. Very excited and lil bit confuse and i need your suggestion guys on my selection as below mentioned.

PC: Mini ITX PC with Intel J1900 2.42Ghz Quad-Core,4 GB RAM,120 GB HDD W/O WiFi, USB Keyboard, 13" Touchscreen Display.
LCNC: Current Master 2.8
BB: Mesa 7I76E
Servo: Delta ASDA-B2

And I have to integrate MPG Encoder with 4 Axis selection and Feed override physical controls where i have some confusion that
-> If suppose i supply 24V(DC) to field power (TB1) and 24V(DC) to power (TB3) connections then i need to supply 5V to P3 ?

If you apply 8-32V unregulated power to TB3 you do not need to connect to P3

i am using 24v SMPS will work