Supergun Questions

Hi everyone. I recently bought this smallcab supergun> .
Here is the website: smallcab.net/supergun-light-p-270.html#.U3FWQfldVno. It outputs audio through a mini jack port. I'm thinking of purchasing a regular 8 ohm arcade speaker to receive the audio. Now the question is, how do I connect the speaker to the supergun, what cables should I use?. I thought of purchasing a 3.5mm Mono In Out Stereophonic to RCA R/L Y-Cable Audio Male/Male Cable, connect the mini jack to the supergun, then cut away the L and R RCA connectors then solder them to the speaker. Will it work? If it does, which side would go to the - and + of the speaker. I've never done this, so please suggest.

My other question regards to controllers. This supergun only has ports for Neo Geo Joystics. However, Neo Geo Joysticks only have 4 buttons, and I want to be able to play games that uses six buttons as well such as SF2. I am thinking of purchasing a Neo Geo joystick DB15
cable:

, then wire it up to a regular 6 button fightstick using this schematic:
The question is, are fightstick buttons different from arcade buttons? Will it matter? Is it possible to make the connection the the DB15 cable? Also, will I need a kick harness or just wiring up the buttons suffice?

The questions is lengthier than I intended. Please excuse that. I am open to any suggestions. Thanks.