What's the volume of that pot?? it's definitely more of a curve than a sanke keg. If you're using a fitting with high temp o-rings, you might have a problem. Even with a keg, you have to tighten the fitting REALLY well to get the o-ring to seal. With a pot like that, I'd think the best way would be to get a couple of stainless pipe washers (one for inside, and one for outside), and bend them to conform to the curve of the pot. Then put the o-ring between the washer and pot.
Your sure-screen will work fine. Fit it over a piece of soft copper (refrigerator) pipe (you can find it in any hardware store), and use a compression fitting to connect the pipe to the valve fitting you're going to install (it's even easier than it sounds).
Here's a directory of links homebrew systems.
Homebrew Systems
Some of them are really worth checking out for detailed design descriptions (some even have schematics).