yes you can, ill put the limit to 3 characters, just so you dont over protect yourself too much. and you dont want too much people either, they slow you down and make you run out of food quicker. but they are good to have because some are good company and they can protect you at times.
The story will be narrated. In the begining I will narrate what your objective will be and what you will have to do next. The choices you make will affect the outcome of the story. Topics wilk be set up by chapter and location. For example the first location will be called "Chapter 1 Grand central terminal/station". You will be coming of the subway train to see the zombie apocalypse happening.