I just did the Brembo brake swap about 3 months ago. The calipers are a fairly inexpensive part of the whole deal ($400 for a brand new pair). I couldn't find aftermarket wheels I liked, so I did the ARP studs ($150) and a set of spacers from motorsport-tech.com ($200 shipped for 4). I like the Motorsport spacers because they custom machine them per application - mine are 13mm thick and they are hubcentric and also have a lip for the wheel to sit hubcentric. Now, the downside is that I had to machine off 1/4" from the snout on the hub so the spacers would sit flush (if you did a set without the wheel lip they would fit without machining, but your wheel is not going to line up exactly with the hub either). Also, while I had the hubs getting turned down I had them remove the 70mm step for the front rotors, so my Cobalt rotors slide on without getting the center hole bored out. I had the machining done for free by a friend, but you're probably looking at $100 or so to have it done. I used a set of Centric rotors from tirerack.com ($135 shipped).
Honestly, if you can find a set of aftermarket wheels you like it would be a hell of a lot easier than changing out studs, machining hubs for spacers, taking everything apart, etc. And it's probably not much difference in price if you go with 18's.
Another thing, those 1" spacers you're looking at are going to make your wheels stick out pretty far. My wheels are exactly flush with the fenders with 13mm spacers.
All my pictures are at home on my computer, but I'll post some up later.