Master Forge Vertical Charcoal Smoker Review with UDS and ot 

you definitely need a vent at the top. parted out an old weber smoky joe and used the cooking grate for the cut out charcoal pan. also suggest lid gasket for 'the egg' ($15)peel & stick on lid makes it easier than rope gasket from oven. didn't do the bottom vents but needs it. holds temp well but no way to control. won a competition 1st time using. found out it is way too small though. had to cut rack of ribs in half just to fit on grate. standard rib racks wont fit inside grill either.

What is the heat resistant tape you used in the door seal called, and where can I get it?

Thats just metallic duct tape. The kind commonly used on A/C duct. Can find it anywhere.

If you cover lower vent up like that, fire will starve. Looks like you have never used it-why not use it at least 5 times before you start doing science experiments on it?