Exhaust leak ?

When it rains it pours! My a/c still on defrost my brake fluid disappearing I fixed that tiny hard hose or so I thought that goes to the firewall so took out my seats and pulled out my carpet to follow it inside till I got frustrated and walked away after a while I get under my truck just looking around and I see this! It's the bottom of my header gasket u ham see a gap where it's not sealed. Nothing is leaking out but could this be the source of my vacuum leak where my header pipes meet the engine? Or is that considered an exhaust leak and that's why I smell gas bad when I start it. Whatever it is it doesnt look right at all! See my pictures any advice?