1- yes, that is the general direction!
2- Mombasa not especially problematical at all. Even if its 'tricky', what is the problem?
3- Any flight can experience turbulence. The flight to Africa crosses the North African jetstream that blows from the west and can cause a bit of bumpiness. Kenyan gets some thunderstorm clouds and the hot ground can cause low level turbulence. I flew Nairobi to Mombasa in an F.27 turboprop. It was one of my roughest ever flights for an hour. So? What is the big deal?
4- Flight time about right.
To any nervous members of your party, you have to be blunt. Either they can hack it and travel and shuddup, or go by train! If they are going to hack it, keep off alcohol, tranquilisers and don't cause a nuisance to others- it is their duty to the other occupants of the plane. Decide- travel and not be a nuisance to all and sundry with a 'personal crisis', or find another way to get there.