China through to India

Hi
I am hoping to fly into Beijing take the train to Lhasa and then travel by 4 wheel drove from Lhasa to Kathmandu via Everest Base Camp. Have a few days in Kathmandu rafting and seeing the tiger sanctuary some where out of town. Then take another 4 wheel drive trip to go overland from Kathmandu to Darjeeling.

I noticed there are package deals that do the Lhasa to Kathmandu trip and blogs about the Kathmandu to Darjeeling. Some blogs talk about poor road quality and difficulties getting to India from kathmandu. Just wondered if anyone has any knowledge of recent trips though these regions. Or tips on where to stay and not stay.