Sounds like a good maintenance routine. I've personally never used seafoam (it's not available here in Mexico). For an engine that has been overheated and rebuilt twice, and a transmission rebuilt once, I would say my Windstar runs great and maybe even better than others I've seen around here.
My only maintenance is engine oil replacement every 3k miles, transmission fluid every 20k miles (actually I've done it once since it's been rebuilt) and plugs every year or so. I don't drive as much as you guys do in other countries and the weather changes aren't as aggressive nor extreme as up north; so maintenance schedules can be a little "neglected" and still be on the safe side.
I'm not saying it's a common practice, but that I'm a bit flexible about it. The only thing I would advise is to stay away from FRAM filters. I've read many times about the anti drain valve being faulty and allowing the oil to loose pressure overnight. I've personally experienced it with a filter I got (it would cause a tapping sound during the first seconds after starting the engine).
I also try to keep the wheels as close to 35 PSI as possible.
Oscar.