I think the postponement of the release dat is due to the release games. They have to have Metroid and zelda at release and I think they are waiting on a final green light from the developers before they set a release date.
Personally I think they need to get the machine out in October. A November release would be too close to the PS3 which will dominate the press and shop space in game shops and games departments. A October release allows all the hype to be centered around the Wii, the empty game boxes, console boxes, demo units etc etc. Then when its released the PS3 hype can start. The sooner the Wii hits the market the better. If you have a console available in October for £150 then people will know the PS3 is £425 and maybe, just maybe opt for a Wii.
With regards to the worldwide release I feel this is vital, they need every advantage they can get to boost Wii sales, a worldwide launch is good for the press and people dont feel like they are getting short changed.
I dont think the logistics would be to hard to handle as the launch wouldnt be on the same mega scale as the 360, a rather more low key approach. I can definitely see Nintendo going for a world wide release of the Wii.