With all of four and a half wheels under my belt, let me offer my opinions.
1. I definitely agree about the brass nipples. I recently had to replace some damaged spokes on an Ultegra/Open Pro wheel (my half-wheel build). I had rounded off a couple of the nipples truing the wheel before I replaced the spokes, and when I broke the wheel down I found significant corrosion on a few of the alloy nipples, so I replaced them all with brass.
2. I built my first set of wheels with double-butted spokes and later used straight gauge spokes for my second build. It's crazy how much easier the process is with straight gauge spokes. If I were rebuilding the first set today, I'd still probably choose double-butted spokes because they suited the purpose and I have a little better idea what I'm doing now, but if I were back in the position of doing my first build, I don't know. That said, double butted are apparently both stronger and lighter.
3. I've got a pair of wheels with the Formula hubs, and I've never had any problems with them. I'm not convinced they're the same as the Novatecs. Both seem to show up under many different brands, but a number of people seem to believe they're different.
4. My fixed gear wheelset has Mavic CXP-22 rims, and I've been very happy with them. I've also had no problems with my Open Pros. I've used both sets (both 32-spoke 3-cross) for cyclocross racing and commuting and generally beat the crap out of them, and they take it. Like you, I weigh around 200 pounds. I have no opinion positive or negative about the rims you planned to use, but I can say I would recommend either of the afore mentioned Mavics.
5. When hitting unseen potholes, it's usually the front wheel that takes the shot. I'm not sure I'd want radial lacing for the kind of riding you describe.