Update;
Had the motor checked out by a mechanic and he found injector five wasn't firing as it should have been. He cleaned out the injector and removed a bunch of debris / carbon that had collected in there. He said the beeping wasn't oil caused. He checked oil pressure and oil supply and all that, and it all checked out just fine. He also said that the injector not performing as it should have been may have caused the sudden drop in RPMs that I was experiencing once in a while. This is where the engine would drop 500RPM for a split second while cruising at or around 3-4500RPMs. So we will see. The starter install I did checked out just fine also, so I was glad to hear that.
So all is good for now, I haven't taken it out since the repair, but I'll post an update.
Next up is the tilt trim motor, it's starting to go now. I can hear it chugging along and "dying", lol. It looks like an easy swap out, but getting into the bolt behind the trim motor against the transom looks tricky. Any ideas, besides removing the engine?