[11-3-2017 18:42:08.694] setting up new cop: null
[11-3-2017 18:42:08.694] setting up new cop: null
[11-3-2017 18:42:08.694] setting up new cop: null
[11-3-2017 18:42:08.694] setting up new cop: null
[11-3-2017 18:42:10.160] LSPD First Response: PlayAction: Failed to find UNIT_RESPONDING_DISPATCH, reverted to random voice
[11-3-2017 18:42:12.719] LSPD First Response: PlayAction: Failed to find UNIT_RESPONDING_DISPATCH, reverted to random voice
[11-3-2017 18:42:16.780] LSPD First Response: PlayAction: Failed to find UNIT_RESPONDING_DISPATCH, reverted to random voice
[11-3-2017 18:42:18.222] [TRACE] Died or dismissed from pursuit
[11-3-2017 18:42:18.223] Free cop
[11-3-2017 18:42:18.223] freeing
[11-3-2017 18:42:18.223] Release control
[11-3-2017 18:42:18.223] [TRACE] Removing ped from ChaseController #1 (GameplayMandatory)
[11-3-2017 18:42:18.223] [TRACE] Freed cop in chase
[11-3-2017 18:42:19.162]  584836
[11-3-2017 18:42:21.613]  586769

This is perfectly normal behaviour for LSPDFR. These messages are used by the developers to see what happened when during execution of the code. If you want to know exactly what each message means:

"Setting up new cop: null" means that LSPDFR recognized a new ped as a cop and takes over his behaviour. The "null" part is probably some kind of optional variable that describes something that is special (or in this case isn't) about that specific ped.

"PlayAction" means that LSPDFR is looking for an audio (speech) file with that name for a ped (Like "We're in the little coffee shop around the corner. "). "Failed to find" means that there is no such file for that specific voice, so LSPDFR uses a random voice that has that file.
Everything that happens after that means that a cop that was part of a running pursuit is no longer part of it (because he died or was too far away from the suspect). Because LSPDFR has a comprehensive AI for cops, that process has a lot of steps (each of which are described in the following messages). If a "freed" cop didn't get cleaned up properly, the plugin would run slower and slower over time.

What the 6-digit-number messages mean, I have no idea. Keep in mind that these are only educated guesses, and that those messages are mainly intended for the devs of the plugin (in this case Sam and the others) to find out in which part of their code something went wrong and to help them find and fix bugs.