I would not take a wire brush, or anything else for that matter to that oil pan unless you are prepared to replace it, which I strongly recommend. I had a Ford Aerostar we used for a beater and for city jobs. The paint on the oil pan didn’t look as bad as that. One day during an oil change I got ambitious, I was going to clean it up, prime it and paint it. I took a rag with mineral spirits to clean it up a bit before prepping it. The pan started weeping oil. I drained the oil over night, cleaned the pan and formed lead flashing to the shape of the bad area and glued it in place with gasket maker. The repair lasted two years until I junked it. It wasn’t worth the time or effort to replace the oil pan.
In your case get an oil pan and replace it. If that lets go you might not be lucky.
I can’t comment about any of the other areas, it would be best to get under it and actually poke around.