1) definitely go to the grand canyon if you haven't been.
2) i hope there is, because I'd like to do the same thing soon.
3) i have a tethered modem plan on my blackberry with Verizon. It provides EVDO for only $10 a month on top of my voice plan. Pretty sure its unlimited(but I also thought SMS were unlimited for $10/month, and its actually only 500, so don't take my word for it).
4) Maybe you can wait on the new blackberry or iPhone? GPS, EvDO, camera--all in one package.