You connect the positive first because it changes nothing by hooking up the ground first you have now given the battery a circuit and is now considered "hot". The reason why any battery would spark while connecting the ground is because somewhere in the circuit something is drawing power, whether it be the dome light because the doors open or the simple constants to clocks and radios. All of those things would cause the battery to spark a little at connection.
i bet you 2 dont charge the caps in your amps before hooking them up ether guess im just use to 20,000 watt plus systems
I'm talking in general. Not system wise.