Keggle parts and fittings?

I managed to find someone to do the plasma cutting and TIG welding required to turn my three 1/2 barrel kegs into useful brew vessels ... best part is, they're going to do it all in exchange for a 5 gallon batch of brew!

I'm not at the point where I need to be thinking of going all grain, so I'm only going to be using one of the kegs as a boil kettle for the time being. That said, I'd like to go ahead and get all the welding done while the offer is still fresh.

Since I don't really need ball valves and whatnot just yet, I'm assuming all I need to complete the welding is a bunch of 1/2" stainless couplers such as these? If so, where is the best place to buy these?

I'm thinking of doing three bulkheads per keggle, as suggested by Bobby_M. Is this overkill and not necessary, or is it worth it to go ahead and go that route while I have access to some free welding? Can I just get plugs of some sort in order to use the boil kettle without all the necessary fittings?

Why not just buy the ones in the link you posted. Looks like a decent price.

If you can get 3/keg for no more than 1/keg, I'd do all three. You can decide later for yourself it it's overkill or not.

Or you can sell them if you decide to never go all grain. I somehow suspect it won't be a problem.