1)I'm personally unsure about the old dex and it's officiality. Keep in mind that the neo-dex has it in the middle of a few other non-legendary pokemon as I recall...
2)Ghost tower is actually the enormous mountain to the south-west of the shopping center town, in the middle of Sea Route 122. Wheter it's at the top of the TOWER (a building "inside" the mountain) or at the top of the MOUNTAIN is something I'd be interested to know.