I have never done the 787 to China, but have been on their 787 business class product. The seats are true lie flat, and are comfortable enough. I wouldn't have a problem using them for a long haul flight. I can't speak to what meal service you will receive on that route. I have been on shorter routes and found it adequate, but nothing to write home about.
I have Club Premiere, and just use that number when booking on Delta - your status transfers - I am Platinum on Aeromexico, and that put me as Platinum Medallion with Delta (which in turn has gotten me free upgrades). I prefer Club Premiere because it is simple enough - there is no spend/MWM, etc. You simply get status mile accrual based on your fare class, and various bonus miles based on your status.