secure; trusted to do this right; discreet

[Klpno]

Hello everyone
I'd like to ask about some things in the following passage.

Then Vega replaced his helmet, and he found himself assaulted by GDI chatter, but what caught his attention was Hastings's voice: "The town is secure. Repeat, the town is secure."
Vega looked around and spied someone he trusted to do this right. "Brodeur, secure this prisioner for transport back to base."
Smiling, Brodeur just gave Vega a thumbs-up, and then walked over.
Opening a discreet to Hastings, Vega said, "Major Hastings, this is Sergeant Vega. Units Gamma and Epsilon have a prisoner."

1. Does the phrase "the town is secure" mean "the town is seized and under control?
2. Does the phrase "someone he trusted to do this right" imply that Brodeur was the most appropriate person to deal with the prisoner?
3. Does the phrase "opening a discreet" mean "opening a conversation"?

[Jamie (K)]

[Klpno]