1. There are entrances to the tunnels, yes! These are both the exits and entrances. Security detail does involve enforcing curfew, but the curfew shift starts just an hour before.

2. They're flown there! It's hard to get to them - otherwise, during the war, the humans would've successfully launched an attack to stop the AI's gains. It's hard to get there, and the humans are also largely without any resources to pull off a sustained attack.

When captured, they're picked up in transports and flown there.