A few minor electrical questions (68 Barracuda Dash).

1....This very simply branches out "somewhere" in the harness feeding between the TS switch connector and the bulkhead connector leading to the front TS lamps. I don't recall off hand. According to the diagram this happens right at the TS switch harness connector. Look at the connector and see if there are TWO light green wires coming out of the connector. One goes through the bulkhead, the other goes to the cluster

2....I think this is "as normal" as you can expect. You could take an ohmeter with engine off, disconnect oil sender, and see what the resistance is. It should read at least 70 ohms or higher. These are mechanical internally, so are subject to failure, as is any other device. The operate "sorta like" a mechanical gauge hooked up to a fuel sender!!!