The square 4 pin plug is for the lockup torque converter. The harness should come out of the firewall through a 2 1/2" or so round hole just out of sight in your last picture. You can see it in my picture between the wires for the heater/fan & the transmission dipstick.
You will need to remove the trans. pan to access the rest of the lockup harness.
As bake noted...The switch on the transfer case is for the light.
For your TV cable, you shouldn't need any sealant, but a bit around the hole wouldn't be a problem.
The "thing" in your last picture is the distribution block. The 12v power from/to various places meet there (big Red wires with terminal rings) so yes, unless your going to change the normal routing/design of the electrical system...you need it & the wires that go there.
Now my turn to ask a question...What is the Black dryer vent looking hose for?
Good Luck with your project. Lorne