Terry,
The wiring is looking Great!
Floorboy,
The black thing is a Starting Isolator with an integrated Automatic Charging Relay. The SI helps keep your electronics from getting fried when starting your motor.
It works in tandem with that battery switch to run batteries independently of one another while charging them simultaneously and governing the charge returned to each battery by the alternator thus they don't overcharge.
One battery can be dedicated to start motor the other dedicated to providing power to your electronics (house battery). When "on," both are on, but battery 1 can't suck the life out of battery 2 or vice versa. Keeps you from draining your batteries if you left the tunes on all day or whatever. If a battery system fails or drains, you can still "combine" the circuits drawing from the good battery to pick up the slack. The red things are Maxi Fuses to keep those cables from cooking anything.
Blue Sea Systems is doing some cool stuff. Their on line catalog is a wealth of information and their tech dept. is one of the best groups I've had the pleasure to talk to. Here is some info:
http://bluesea.com/category/2/productline/overview/329
http://bluesea.com/category/5/21/pro...e/overview/127
ps Congrats to Saugeye on getting Entourage, very cool to have a couple of Sceptres up there.