Hi Grog. I hope you can speak chinese.

from Xiamen, take a bus going to Yongding(永定）。go to Songbai(松柏长途汽车站）long distance bus station, you can book your ticket there or buy then leave in an hour or so. Tell the bus conductor where you want to get off(we did at Zhencheng lou, many people get off there). From there, you can start visiting the tulous. the king of tulou, chengqi lou, is 4 kms from there. you could either take a motorbike or car for a 3~4 hour tour. the car would be much cheaper as you could share the costs with 3 other people.

from Xiamen, my friends took the train to Wuyi. if my memory's not wrong, it took them around 8hrs. haven't been there so I have not much advice. good luck!