In fact there is no right order, you can even start immediately with the Black one ;)
In fact the 2 Sqn are going together on the same line, one supporting the other one. For that reason you dont pull 10 (2x5) tokens.
Yes you can have 3 Sqn and 9 tokens.
No the leading Sqn is the one that inflict the Damage. I you want the 7, it has to be the leading sqn.