These are some of the most popular. Most asked about content.

Weapons Related

Zaxis's DPS Calculator
Weapons Basics
Wind Up, Wind Down
Penetration
Armor Types
Critical Table
Target Table

Veterancy Related

British Veterancy
Veterancy Points

Cover Related

Cover Tables
Smoke

Other Useful Information

Stacking Resources
Weapon Drops
Upkeep and Population
Experience Points