Congratulations to your decision. I have the M8 since 01/07 and enjoy it immensly. You already got good advice, but I thought I would throw in my 2cents.
- Buy a demo or refurbished M8 from a reputable dealer, simply because of the warranty (Popflash, Kurland etc)
- 35mm or 28mm most likely will become your most used focal length. I never got along with the 28mm, but like the 35mm.
- If I would start all over again, I would only buy those Leica lenses which are unique or simply best in class. As far as I'm concerned the only "must have Leica glass" presently is the 50 lux asph. Otherwise, I would buy Zeiss lenses, the ones I have (or had) are superb in performance, and build quality, costing a fraction of the Leica equivalent. CVs can be from good-excellent, but sample variations (maybe except for the Nokton 35 f1.2) and lower build quality explain the price difference to the Zeiss lenses.
- A subscription to Sean Reid's webpage is highly recommended, to learn about the many excellent lens options available.
- For your NY stay, a wide lens is recommended (21mm or 24mm), maybe accompanied with a CV 15 or 12mm, which are great value for the money and fun to use in the Big Apple.