For Police work you will need a minimum of 1500 total helicopter time of which 500 hours PIC overland in VMC( to include a significant proportion of low flying), with a minimum of 50 hours night of which 20 must be PIC.
Some forces require more. Wages are around 33 to 37k for forces who use contract pilots, and around 42k, ( I think), for those forces who employ pilots direct.