If we're gonna imitate real life in my country at least, firstly they'll be able to do road blocks in search for drugs and enforcing highway laws, usually when we have no work we do basic training such as roleplay radio procedures, IS situations ( riot control situation) Infantry training, Vehicle specialization if we get tanks, apc's or even jets for example, Weapons training should be a regular thing as well with shooting practice also, the rules of engagement theories (ROE theory), and much more that's not coming to mind at the moment. As for weapons being stolen i say make it like the LSPD where their weapons can't be stolen.
Also i thing that should be is a rank of low status (Recruit to Staff Sargent) should not be able to arrest, only Officers have the authority to arrest criminals, low ranks can only detain and wait for either the police or a high ranking officer.