Please Help identifying underhood components

Dana is correct. Mako21 elsewhere has posted that his car is 1976.
You can search FABO for a pdf of the 1976 wiring diagrams that 67Dart23 has posted and that I've tried to help people with understanding.
It is very important to understand how a '76 is wired differently from the previous years before mucking with it.
Adding the headlight relays (using Stern's parts or crackedback's) will still be benificial.
Do not add a wire around.
No need to mess with the ammeter or the wires to it.
Cleaning connections is fine but observe that the '76 has multiple fusible links that as far as I can tell are crimped/welded or similarly joined into the lines. If so, don't try to pull them apart.
If you like the idea of LED's, Stern is probably one of your best sources of info and guidance. I personally see no advantage but to each there own.