How would I set this up so that the heli comes every 2 hours? 

I use these settings , you just adjust the timers (in seconds) for what you want.

  "Spawning - Automatically call CH47 between max seconds": 5500.0,
  "Spawning - Automatically call CH47 between min seconds": 3500.0,
  "Spawning - Automatically call CH47 if one is already flying": true,
  "Spawning - Automatically call helicopter between max seconds": 6500.0,
  "Spawning - Automatically call helicopter between min seconds": 3100.0,
  "Spawning - Automatically call helicopter if one is already flying": true,
  "Spawning - Chinooks to spawn": 1,
  "Spawning - Disable CH47 default spawns": false,
  "Spawning - Disable Helicopter": false,
  "Spawning - Disable helicopter gibs": false,
  "Spawning - Disable helicopter napalm": false,
  "Spawning - Disable Rust's default spawns": false,
  "Spawning - Helicopters to spawn": 1,
  "Spawning - Max active helicopters": 4,
  "Spawning - Use custom helicopter spawns": false,
  "Spawning - Use static spawning": true,
  "Spawning - Use static spawning for CH47": true,​