My new 71 Dart and the issues I am finding. Help needed please

In spite of your challenges, it looks to be quite an attractive acquisition (I envy you dude!). As for your electrical issues, consider it takes a positive (+) and negative (-) voltage potential to motivate anything electrical. Integrated into any factory circuit is a fuse, located in the fuse block. I would start by checking the fuses. If the actual fuses look good, the next check is: are they getting power? Check (with a volt meter) if at least one side of the fuse has battery voltage when it should (like when key is in the ON position). The flip side of the coin in an electronic circuit requires a negative (-) supply as well. This is the ground connection. It is possible that you have power+ and ground going to your starter (and maybe even your ignition coil) where the engine runs. However, few (if any) of your accessories work.

With that said, I suggest checking the fuses; making sure they have battery+ voltage to them. If they check good, check ground wires. You should have battery ground-to-block, battery ground-to-firewall/inner fender, and perhaps other grounding wires. To verify, a volt meter can verify both power+ and ground- at individual accessory connections. There really isn't any more than that.