Hi Ian
This link to the LG might be relevant -
http://www.london-gazette.co.uk/issues/28988/supplements/10116. If you check the LG further you might find when he was transferred to the RAOC and received the honorary Captaincy. The OAC became the ROAC in 1918.
Regarding the MIC, officers had to claim their WW1 medals. Other ranks received them automatically. In the remarks IV is issue voucher and the date 8 Dec 1921 will be when they were sent to him. I am unsure of EF 9, but this probably refers to when they received his claim.
(1) does mean France, and this is extra information, as normally this is usually only with pre 1916 dates to justify the award of the 1914 or 1914-1915 Star. Notice at the very bottom (in red) 10/19 stands for October 1919 and is when the design of this MIC was finalised. It surprises some people how long it took for men to receive their medals.
Ken