How to work in team on one VMware image?

For one project, four of us got project to work on VMware virtual image, OS is CentOS. We have to do our project in MySQL workbench, R language, and some other programs.

1. What is the best way work together as a team?

2. What program to use to sync our work?

3. Can we for example work at the same time all of us on different computers and somehow sync our work?

4. Are there any free, student tools for working together?

It is unfortunately essential to work in virtual image, because the work has to be accessible and given to others.

This is our very first experience working as a team on large project so we are a little confused what is best way to work together.

If I can provide you with more information, please ask away!