From this meeting, you should be able to write a project plan covering all that has been agreed. You should send this to the artist with a contract for the work and circulate it to relevant people in your organisation.
The more comprehensive your plan is the less likely you are to encounter misunderstandings later on. However, you may need to adjust the plan as the project progresses if unexpected circumstances arise. Make sure any changes are clearly agreed with the artist and are achievable within the original budget. For large projects, it may be worth agreeing on someone who can arbitrate in the event of a disagreement or grievance. This could be an internal manager or an external body such as an arts education agency or arts officer.
The project plan can also act as a checklist to ensure that you have sorted out all the practicalities in advance of the artist arriving. Make sure you have prepared the group for working with the artist, arranged facilities and materials and informed everyone of their role.