this may be a bit late for your trip but maybe not.
I use a Nikon 990 for work everyday great camera, burns through batteries big time. I used a 950 for a while, the battery cover is crap kind of cheesy. I havent heard of a car/bike adapter but you might look into rechargable batteries, 2-3 sets, and a solar recharger. I use a Mac Ibook (older blue plastic) I have found them reliable, OSX is very sturdy, instant download from the nikon.
Consider what you will do with the photos once your nikon RAM is max'd out, if you load them on your hard drive the computer could be damaged or stolen. if you have an internet connection with your mac you can upload your photos to apples Idisc online storage, free too!
Remember Jpegs are good for sending via email but save in a TIFF otherwise jpeg will lose quality everytime you save them.