I completely disassemble, soak in oxyclean, then rinse, reassemble, and sanitize.
It's a total PITA and probably way overkill, but I can't sleep right if I know it wasn't done perfectly.
I dry hop in secondary... some people dry hop in primary right before the end of fermentation.
There's an episode of it on Jamil's show from The Brewing Network that is quite informative.
Just to add an update: I have brewed two batches of this beer, one pitched with S-04 and one pitched with WLP029 German Kolsch Yeast. There is a difference.
The first batch (S-04) doesn't have the fruiter, crisper finish that kolsch has. Now, the S-04 batch has been chilled and on gas for a...
I remember Jamil talking about this on his DMS Podcast IIRC. His input was to create a boil just to where the surface is broken up. You don't want slow swells, you want the surface to open up a little.