One of the terms of Riley's parole is that she is not allowed to access a computer. Even though the SWATing was for a wrong reason, she was actually violating her probation by helping her father and would have been sent back to prison. Matty would not have been able to get her out without blowing her cover.
The chemical weapons were stated to be white phosphorus. White phosphorus is commonly used in smoke grenades, tracer 'illumination' rounds, and incendiary munitions, but would not be considered a chemical weapon; The term chemical weapon would be applied to a toxic chemical or its precursor that can cause death, injury, temporary incapacitation or sensory irritation through its chemical action.
Desi puts her hand to her right ear when listening to the radio patch-in through her comm. Later on, she does the same to her left ear when talking to Phoenix.