My top one would have to be Vrare after that seeds project. As well as Golf app project
1) the relevance of having a team is it prepares you for the workplace. Since in the real work environment you are going to be working with others on projects. It will benefit you in the long run.
2) Manage a team by having an agile format in which everyone works on one section but still keeps up with each other. Make sure to have to do lists that will have dead line dates that way.