Lots of great builds here and there are multiple ways to go. To answer your question, yes they hold temps like a rock. For tools you can get by with a drill with a step bit that goes up to 1" (harbor freight has a cheap step bit set for under $20) and a cheap jigsaw with a metal blade (once again you can buy a cheap jigsaw at harbor freight for right at $20.
I have built all of my mini's using the SMJ silver. I found mine cheap on Craigslist. If I hadn't I would have bought the silver as the stores in my neck of the woods don't have the gold. Here's a quick list of parts you may need if using a silver, minus the pot and the BBQ.
Ash deflector - tin can with holes or small stainless pet food dish
charcoal basket - 1 x 2 sheet of expanded metal for the sides. You will use the charcoal grate that comes with the Smokey Joe for the base.
Side air vents (SMJ silver only) - (2) 3/4" black pipe nipples, (2) 3/4" ball valves
Heat deflector - (not required but useful for low temp smokes) 10" terracotta planter tray cover in foil.
(3) nuts and bolts to make supports for rack.
There are a few other items that aren't really required, therm paint, etc...
As for builds I'd read through the forum and take in all that you can.