Exactly sequence of alarm signal sent to monitoring center

I am new to the SimpliSafe system. Just started hooking it up 3 days ago. Unfortunately the speaker in the base station has already stopped working and I am awaiting my replacement. I do have questions regarding the exact sequence of when the monitoring center is notified in the event of a break-in. 

Obviously the biggest concern with the system is that a would-be burglar could unplug the base and possibly remove the batteries before the siren would blast due to the inability to change the entry time in away mode. 

1) once the siren is blasting, what happens if it burglar unplugs the base?

2) once the siren is blasting, what happens if a burglar unplugs the base and then removes the batteries?

3) how long does it take for the monitoring service to get the alarm signal once the siren begins?