1) Co-creation is a strategy where diverse stakeholders collaborate and produce a mutually beneficial product/service together. Therefore, the experiment should treat the expertise of multiple stakeholders as important throughout the whole process of product/service development. This can be done, for example, by hosting regular co-creation interviews, workshops, sessions and other activities/events. It is not necessary to engage into co-creation activities before starting the experimentation, just describe in your application what you intend to do and why. You can read more on how co-creation goes beyond user testing at http://organicity.eu/co-creation-and-why-we-need-it/
2) Yes, the question refers to skills and experience that the team members bring to the experiment. Co-creation skills are those that, for instance, will allow experimenters to engage with citizens and other stakeholders, analyse data and facilitate service/product co-creation in other ways, relevant to your experiment.