The fee must have been settled by Freie Universität or a Freie Universität member. The invoice must be assignable unequivocally to a corresponding oder submitting author at Freie Universität.
Yes. However, the author's Freie Universität address has to be given as official address – either exclusively or in combination with another address.
Even if journals have not (yet) been registered with the DOAJ, publication fees can be covered through the publication fund. In all cases, journals must be genuine open-access journals, and according to the German Research Foundation's regulations, they must have strict quality-assurance procedures in place.
That is correct. The regulations exclude funding in that case.
No. That is impossible: Once payment has been made through an external-funds account, reimbursement to a regular-budget account is excluded.
Funding through the publication fund is possible, on condition that there is no provision for publication costs in the project budget.
The critical factor is the invoice date. Funding is allowed only for fees invoiced during the current financial year. Please make sure that all invoices are submitted to us by the end of January of the year following the year in which they were issued.