Hi,
Ans 1: Yes, you can post MIRo against a PO whose 107 is done and pending for 109. In this case, system wont automatically default the quantity and value. you may manually fill it and post the MIRO.
Ans 2: You can post MIRO against a po for which the material is not yet delivered. Only thing is you have to remove "GR based IV" tick mark from the Invoice tab of PO. In this case also, system wont automatically default the quantity and value. you may manually fill it and post the MIRO.
Regards,
AKPT