I'll be glad to answer anything I can on it.
1. Yes, I considered the Pioneer, but I had better/more reviews on the JL sub so I went that route. JL had a rep for great quality products, so I chose that route. Nothing against the Pioneer though.
2. You run an aftermarket amp, and it depends on the configuration/specs on the amp as to how it is wired. Determine what configuration the sub is (dual/single voice coil and the ohm rating) and the amp (mono, two channels, 4 channels, etc). Take that info, and use
this page to show how to wire it.
This method is what I used (mono amp, 4 ohm SVC sub). If you have questions, let me know your amp/sub configuration and I can offer more input if needed.
3. The only mod I had to do to the box was remove the ribbing, very easy to do. On second thought, I did add a terminal for easy hookup. All this did was allow me to attach wires to the box and have a tight seal.
4. Extremely happy with results, I've had no issues with it at all. I've had 4-5 different sub setups and this is by far the best I've had.
Feel free to post or PM any questions you have, I'll do what I can to address them. If something isn't clear, feel free to ask for clarification.