Helicopters
Use the following trick to find a helicopter with weapons. Spawn at the Agency island. Look at the gate to the bridge. Climb up the building to the right of the bridge. Look straight ahead after climbing to see a landing pad with four helicopters on it. Note: Level 5 Agility is required to reach them. Note: The helicopter closer to the Agency tower, and across from that, has missiles. The other two have machine guns.
Use the following trick to find a helicopter with guns. Spawn on the island northeast of the Agency island. Once in the middle of it, climb the highest tower there. When you reach the middle level (with the free standing balconies), you will find a helicopter with no guns.