Last time I did LHR-NRT in J we we're given slippers which are normally an F amenity. Was told it is because the Japanese people are much more hygiene conscious than Westerners...
Someone on that flight was obviously sooo much into hygiene that the Elemis products in both toilets on the UD kept disappearing! I wish they had searched everyone's bags at arrival for a laugh
I do not remember the meals but they had Japanese options and I remember chopsticks. And a very deferent Japanese crew member.
As to seating it depends on how much you guys plan to chat. Personally I would take a window pair for you and your wife, and have your bro at a window behind / in front.