A buddy of mine suggested I change the oil once it reaches operating temps just to get all the assembly lube flushed out and get some fresh oil back in it for the break-in. I never did that before but I figured what the hell, it definitely won't hurt to have fresher oil in it.#1. And why are we changing the oil after start up? Unless you have contaminated the oil in some way w/ gas, or water/antifreeze,....leave it in there at least for the initial break-in (If it's a new motor).
#2. Buy a test light. They're cheap, and will tell you instantly which circuit is hot.
#3. as for which fuse,...I'm not the one to ask. I don't have a stock, (and haven't had ) a stock fuse panel on a Mustang since '12.
The last time I was searching trying to figure out why I couldn't start the car we were trying to figure out why the fuel pump wouldn't get power from the "key on" position and we came up empty. The only thing we didn't check was the inertia switch. I'll check that next time and go down the checklist @jrichker just posted.