Basic Sub Installation (noob) Questions re wiring

So I've been reading extensively about the various threads adding either the Kenwood or the Bazooka powered subwoofer into the system to improve the sound. Thanks to the posts in here I feel pretty comfortable as to what needs to be done (i.e. splice the rear speaker wires, to tap a signal, run power to the rear battery).

Problem is, I have never actually installed any car stereo equipment in my car. So far I've taken all my cars to professional installers, but I feel that it's about time to get to know the guts of this one as I plan to have this Prius for a while. So with that in mind I have some very basic questions regarding how to cut and splice the wires.

1. Rear Speaker leads: based on earlier advice, I plan on tapping the leads near the JBL amplifier under the seat (I have the JBL system). When doing this, is there a minimum distance that i should cut the wires away from the amp to leave enough room to work with future wiring. I presume it is safe to do this with the car off, or do I need to disconnect the battery somehow as well.

2. "Splicing" - I presume the process of splicing is simply cutting the wires, stripping maybe a 1/2" of bare wire on all the leads and then taping the old amp end, the old speaker lead and the new Sub lead together so that all the wires are touching. Is there a better way to do this other than the old "twist and roll" technique, followed by electrical tape? Do you guys use any special crimping tools or connectors to get reliable, clean connections?

3. Connecting the Amp - in the various posts I saw that people are connecting their powered subs directly to the rear battery positive and negative. Even though I have not installed myself, I remember that it is a good rule of thumb to insert a fuse within 12 inches after the battery. Should I plan on adding a fuse block just to be safe? Also, I remember reading that you actually only need to tap the positive and attach the negative to an exposed piece of metal frame. Again I am interest in any parts that would make the job cleaner and easier .

I know these are some very basic questions, but I want to make sure I do a clean job in case I want to make more mods in the future

 

To answer part of my own question, this is what I found about soldering and tapping wires:

Connection options, splicing wires and how to do it right, and WRONG!

I thought it looked very informative.. Still have the questions regarding the distance to the JBL amp (best place to tap) and also the need to connect the negative as well as the positive runs to the battery.