If you want to go top of the line... Check out Cabellas and their bear proof coolers. They are awesome! Spendy for a MLT though. Any decent coolers works great. I've used Coleman extreme coolers to great success. Get something at least 60 quarts though, you need the space for big beers. The round 10gal drink coolers work well but limit you a bit due to size only being 10 gal.
For the stainless weldless, find the cheapest place you can find 2 washers, 2 thick silicone gasket, a 1.5" nipple, nut, and full flow valve. 1/2" is fine for the stuff. Some say 1 silicone gasket is enough, but I like 1 on the outside as well as in. I find it seals more effectively.
I'd use a cpvc manifold in the bottom.