For people who find this and want the final results, these are what I see at my site, YMMV:

1. Links from image maps are indeed followed, Google crawls pages that are only accessible via the image map. nofollow also seems to be respected, unless Google just decided not to index these pages for another reason, but I doubt it.

2. The images are indeed indexed for Google images as one image containing the entire map. This image gets the "alt" value of the entire image, not the individual map segments.

I hope this is useful.