1. I did not modify my steering column wiring so it would be easy to replace the ignition and turn signal switches should the need arise. I reused the original harness connector
Same as Quagmire, I kept the original wiring harnesses for simplicity of replacement, if needed. The turn signal switch/harness is available as a repro if you want new, not sure about the ignition sw.
I used new light sockets and terminals. When I did my rewiring you could still get all the connectors and terminals from the dealer, but I've seen sockets are available at stores like Napa, Canadian Tire, O'Reilly etc.. . New headlight connectors to make your own headlight harness are available, I bought mine from the dealer. For the connectors I couldn't replace, I spliced them together.
-Use weather sealed connectors where ever possible under the hood and outside of the car.
I used bare crimp-on connectors. I first slipped a piece of heat shrink on one of the wires, then crimped the connection. Then I smeared a little rtv on the connector before shrinking the heat shrink on. A little rtv would seep out either end making me feel it was a good waterproof connection.
Good mechanical protection is important, slip on, tape, convoluted tubing (that purple stuff you see on MEK's engine) etc.. to prevent possible future grounds.