The link has some good designs. If you're batch sparging, the easiest is probably just go buy a handful of elbows and tees and use some rigid copper and have a square manifold with a couple of crosses in your round cooler, with batch sparging it really won't make any difference. Rigid copper's cheaper, and if you're like me, you bang it around a lot and it's less prone to bending.
For hooking it up to the spigot, the elbows and stuff actually fit reasonably tight, and as long as there is liquid flow creating a laminar effect, it's less likely to start sucking in air and losing suction once the liquid level gets towards the bottom. If it doesn't fit well for whatever reason, put some petroleum jelly on the copper sleeve when you slide your manifold on and that'll help. Just make sure you don't make your manifold too big so you can slide it on.
I wouldn't bother soldering any of it, I didn't. As long as you don't use it as a frisbee, it's unlikely to just fall apart, and makes cleaning easier.
Also make sure that when you cut your slots in the copper, have the slots facing downward: helps with getting all of the wort out and also avoid creating too much suction and clogging up your manifold.