In the second one, it's correct. The police have installed... and [the police] are expanding... You don't need to keep the same tense.
In the third one, I don't understand the passage. However, the comment about using a comma if you would have a reasonably long pause would apply. Also, she is the subject and agent of the first part, but the subject and recipient of the passive in the second, so the comma does make slightly more sense.
A strict grammarian would say no comma in any of the three.