so...can you just wire all the negative grounds together and run them back to the battery negative? and for step 5....you get the positive wire connecting to the cig lighter and then cut it? then connect it to the switch and then back the cig lighter?

 

You can run them all back to the negative.
And with the wire behind the cig lighter, you use one of these:

The left hole slips over the cig wire, and the new wire sits in the right hole, and both are clamped down, and connected when you push down the metal part. Then the flap on the left folds over, and closes it.


There is also one that looks like this:

 

Here's some diagrams for you..