I am a big fan of Splinter Cell, so you can count me in. However, I have found some things in your text plain wrong:
1. Fourth Echelon is an independent special operations unit, it answers SOLELY to the president of the United States.
2. Voron is not a sub-division of the CBP (that's SVR in Cyrillic), Voron is a SPETSNAZ unit Within the Operations Department of Directorate S in the CBP. It is based upon the "real" special operations unit of the CBP called "Zaslon". Formerly known in USSR as SPETSNAZ "Vympel".
3. There is no way possible for a simple clandestine unit to be able to take on a secret society that is able to "run Washington, and Moscow, and Beijing and any other place that matters." Not that they couldn't try.
4. Voron has gone rouge, they are probably under Meggidos payroll, just like FBI, CIA, DHS, FSB, GRU, SVR, NSA and the disbanded 3E.
5. As far as I know 4E standard issue handgun is the Beretta PX4 Storm special duty 45. ACP (Used by Sam, Briggs and Grímsdóttir). Only Sam and Charlie used the 5.7mm pistol.
6. 4E official secondary (primary by normal standart) armory was limited too: MP7A1, FAMAS-F2, HK416 and KAC SR-25.