[font color=\'#000000\']Actually the only camera that will really fit the criteria (excepting cost) is the Canon 1D Mark II. None of the point-and-shoot digicams are going to perform well in multi-minute exposures, and I don't think you will be happy with the flare resistance of digicam lenses, either. The 10D/D70 idea is a fairly reasonable option but you are giving up resolution and noise performance compared to the Mark II.
Don't bother with on-the-lens filters when shooting digital except for a polarizer. Shoot RAW, bracket if necessary, and set white balance in post. Warming/cooling/color balance filters and the like are far better done in Photoshop than on the lens.[/font]