I believe most of the Rule
pumps, including the 1500, come in two versions, automatic and manual. The automatic has a built in float switch, the manual doesn't.
So will depend on which one you have.
Short answer, Brown is positive, Black is negative or ground.
You shouldn't just wire the pump directly to the battery
so need to go to a switch or circuit breaker on you DC panel or somewhere so yes you need a switch. You also need a fuse or circuit breaker in the positive side otherwise a jam in the pump could start a fire.
Several different ways to wire an alarm
. Depends on what you're trying to do. Do you want the alarm to go off every time this pump comes on?