Hey Frank, so sorry I didn't respond to your PM!!! But I think you'd get a better response from the forum anyways...
Although I haven't been there myself, the Nismo Omori Factory is a definate place to see. Just use Babelfish to translate that link.
Maybe one of the other guys that live near Tokyo can give you a better idea of where to stay, as I only really know the Makuhari area there (coz of the TAS).
There aren't really any special things you need to consider, Japan is a very tolerant place, you needn't worry about smoking in the street, it's ok!!! Hell, you can even piss in the street if you want to!!! thats ok too...
I'm not sure of any car show and the like during summer in Tokyo, if you came to Kobe I could sort you out, but with only 10 days to play with, your best bet is definately Tokyo.