To my eyes it appears you have a kettle that has sat outside in the sun for some time. It's got some heavy fading and oxidizing beginning. In that case, you can't do anything to make it look better with cleaning techniques. Painting it ultimately won't hold up even if you use good prepping techniques followed with high temp paints. After all its just a plain black 22". Use it for what it is...a solid cooker. It has plenty of life left in it. The inside where it's flaking and peeling under the top vent will come clean with steel wool or a razor, but its really not that important to go through that efforts. My opinion is to just cook on it as is. Wait for another kettle to come along that would be more deserving of your efforts!
Try wiping it down with some cooking oil or spray it with Pam, as that tends to bring the black back, at least short term. Painting porcelain is difficult, so this may be your best bet until you find a grill more to your liking.
Don't paint it! Its a cooker...not a looker. IMHO painted kettles never really look original. Just keep buying more grills and accept the disease.
Pam is a brand of spray cooking oil you find at the grocery store. Get the original, no need to treat your kettle to butter flavor.
Welcome from Wisconsin, what's a SWIMBO? Swimboacronym for one's wife or girlfriend, stands for: She Who Must Be Obeyed"I won't be going to the pub later, swimbo says I'm to paint the baby's nursery today."