I have a design in KiCad, it is a two layer pcb, my main battery (+) track is 50mils and it is on the bottom layer, i am getting it from a through hole battery holder. Now when i use a Via to redirect that Vcc track on the top layer, how much of impact does this Via diameter and hole size have, and how much does it impact in context of power?
Download Saturn PCB toolkit, there is a calculator for via parameters, so you can work them all out. Use the minimum plating value for your via, get this figure from IPC spec or PCB manufacturer... Class 2 is 20um plating.
For power multiple small vias are preferable to one large via.