Question about an English expression
 

Hello everyone,

I'm currently learning military terminology and having trouble understanding the following 2 parts clolored yellow.

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Cujo 2-1: "Vulture, Cujo 2-1 Checking in a flight of two F-35s, orbiting west, 20 miles, at Angels 12. Ordnance to follow:... ahh, four laser Mavericks, two HARMs, six-five GBU 12s, 600 rounds a piece. 0+40 Time on Station. Ready for tasking."

1. I'm not sure what the "20 miles" actally refers to. The two F-35s are 20 miles away from where?

2. I'm not sure what the "six-five" really menas. I understand GBU-12 is a type of missle but not sure what the "six-five" really means.

3. I'm not sure what "0+40 Time on Station" really means. Does this mean the two F-35s will be on station in 40 seconds?

It would be great if you could give me some advice on them. I'd really appreciate your help.