Time to remove/replace Stainless Works headers?

[scorp508]

How long (measured in beers, time, swears, whatever...) does it take to get a set of Stainless Works headers out and back into the car? Do they drop out the bottom or go in the top? I am planning to weld a couple wide band O2 bungs into them. I have a 4-post lift and all the usual tools. I've already had the exhaust behind the headers out, so I can do that pretty quickly.

What gaskets are recommended to go back on with?

Thank you.