The B-pillar is a tough one – no patch panels that I know of. If yours is like mine, the rust you see is only the tip of the iceberg! There’s like four layers of metal all stacked and spot-welded behind the lead and rust seems to form between the layers. Bottom-line is ‘be prepared for the worst’.
The vents are held on by two stud/nuts on the back of each section. Be careful – the studs are pot-metal.
P.S. – Mr. Campo, most everyone on this forum likes to know a little about who their conversing with so please take a minute and fill out your bio – Cheers!