Formations
The hardest element to understand (stagger) is what is explained in this quick 3 minute video: https://youtu.be/NEdOJ6Jf-Jw
As a general rule of thumb, left is prioritized for formations, this means that when forming a stagger, it is done from left to right, same goes for rank order, and same goes for any odd numbers in an arrowhead.
Shoulder To Shoulder (STS)
Single File Line (SFL)
The spacing in an SFL should be wide enough to the point that people should be able to do an individual face at any perpendicular angle (right or left face), and then they would be in a STS, without touching each others shoulders. As shown in image 2.
Image 1: