Hello
We did this trip in January 2010 (we live in Saudi Arabia, but were holidaying in Qatar and Bahrain) and bagged caches along the way. The road is remote and we had no troubles detouring to find the caches. Most of the caches on the way to Bahrain are within 4 or 5 kms of the road. Have fun and happy caching!
Photos: Landscapes are NO problem, but if you want to snap people, it's always best to ask first in Saudi Arabia.
As for registering at the embassy, you can if you want to - it is never compulsory, just highly recommended if there are problems while you are in-country.
me N u