If you want to take fresh food, avocados and bananas are good as they are whole and can be mashed as you need them on the plane.
Definitely BF on the way up and down to stop his ears hurting.
If it's a night flight, be aware that they will take 1-2 hours to feed all the passengers before turning the main lights out. AT his age it's hard for a baby to sleep with all that activity so don't plan on him dropping off just because it's his usual bedtime.
If it's you and your husband travelling, ask the staff to feed one of you first so you can take turns looking after the baby while one eats.
The staff will be as helpful as they can be, it's in their interest to keep the passengers happy (which means keeping you and your baby as comfortable as possible..)
Turbulence: If the baby's in your own flight approved car seat it's no problem. If he's in one of the airline's baby seats for older children that fits onto the bassinette table (BA have this, not sure if others do also) they will tell you to remove the baby asap, put him in your lap and attach the special seat belt - same if he's lying down across a few seats. They HAVE to tell you to do this. But, they will usually only tell you once - then not return to push the issue. Again, it's in their interest to let the baby sleep. However, if the turbulence is really bad they might well come back, of course you might decide that you feel it's safer to move him anyway.
If he cries, try to focus on the baby and NOT what people around you are thinking. It's envitable, those with children will totally understand and as for those without - well one day it will be them in your position and they can always put the earphones on!
Lastly, if you are really worried or feel you need a back up plan, you can ask the doctor for something that will aid sleep (like a mild antihistamine). Phenergan is something they often prescribe but you MUST try it at home first as for some babies it has the opposite effect and they get hyperactive!
Sadly, we've tried it all and my bub is totally immune to all of it...
On the jet lag front, fresh air / natural light / time outside are the best things to aclimatise to the new time and esp when coming back to HK.