Hong Kong, China, Laos and Thailand

Hi,
Our family have done a couple of trips to Thailand, Vietnam and Cambodia. This time we are flying into Hong Kong and hoping to do this- fly to Guilin/ yangshou then fly to Kunming straight on to Dali and Lijiang. Fly to Jingjhong and over border to Laos. stay in Luang Nam Tha then Luang Prabang. over to northern Thailand probably by the slow boat. Chaing Rai.........somehow get to Tha thon. down to Chiang Dao then Chaing Mai then Sukothai. Bangkok. I know the rest as I've been to Bangkok before.
Questions are mostly about transport and especially from Jinghong to Luang Nam Tha, how long? Is it easy enough to hire a car and driver in China? Is there a boat trip from Chaing Rai to Tha thon? What are the treks like out of Luang NAm Tha (my husbands knee is bugging him) plus two kids? (9 and 13)
Any info on any of these places and how to get from them etc would be most welcome.
Thanks
Fran