These are all great additions to enhance the passenger experience and will result in more reviews and tips.
I also provide these things and some individually wrapped candy. I've been thinking of a way to get a small water dispenser and some plastic cups, it might be useful.
I do the same. I always offer items within the car if anyone needs them. I keep those small chip bags handy along with candy and bottled water. Some people have medical conditions that may require them to get something in them to feel better so I like to be helpful.