Your cabins, presuming their 777 or A333 or 380 will be exactly the same. Identical pitch, seat patterns, everything. Their on board product is extremely, almost perfectly consistent. Only the old 747 have older ife and a slightly smaller seat.
You will see a lot of the same food over these flights - bibimbap, Chinese fish and noodles, chicken and rice, beef and pasta. It isn't bad, but it will all taste the same.
Haneda to Gimpo is always a giant, full plane. Quite impressive considering you wouldn't get a 777 from ATL to NYC running four times a day in each direction. You will get a meal, but the flight is so short that you can barely finish a movie.
Hong Kong is a regional flight, so it's just a meal service.
If you look on their website, they have a service schedule of the flight to Paris (when you eat, etc)
Korean Air attendants are very gracious and polite as they are on most Asian airlines. The advantage, I think, is that their planes are consistent.
For instance, Asiana will swap planes two hours before departure. You might be flying to Paris with overhead TV on a loop.