The fund flow should comply with accounting rules.
A donation is usually an amount given to an established non-profit organization with an established charter and its own auditing processes. It is usually not linked to a specific project but just to partially support the overall goal of this organization.
Expenses covered must be related to a ReMo event/project as they occur, or once they have occurred.
Event-related expenses are covered once the event has occurred, besides the case of advanced payment. In all cases such documents/offers should be formalized once the project has been approved with amounts/due dates and bank info or Paypal accounts so payments can be made accordingly.
Individual expenses are covered by paying back expense notes submitted with receipts, to cover individual travel, accommodation and food falling within pre-approved limits/guidelines. In some cases some of these expenses (travel, accommodation) could be directly paid to the service provider beforehand by Mozilla, which then provides the airline ticket or the hotel room to the individual.