Gosh, your 3 x great-grandfather sounds like such a interesting man. It is terrific that you will be recording his life. I am afraid all my ancestors were agricultural labourers and apart from 3-4 generations of criminals and convicts from Biggleswade in Bedfordshire, they are all very boring.
I am a bit of a hybrid - born and educated (if you call it that) in England; worked in Washington DC for a couple of years; lived in and worked at UVIC in Victoria, B.C., and now have been in Western Australia for over 40 years. I am a odd-bod with no less than three citizenships!
No, I'm not a military historian but became a devotee of the Crimean War after visiting the battlefields in 2007. I am a retired training and development officer - giving me a bit of background in presenting talks and lectures. These usually have a historical flavour.
Yes, isn't the Australian War Memorial a wonderful place. I visited Canberra in 1999 and I know it has grown since then. Our WA Army Museum is in Fremantle and its Curator is a Canadian! It was fairly small beans when I first visited some years ago, and was under threat of losing its barracks and land to Notre Dame University. Since it was saved from the bulldozers, it has gone from strength to strengh and is now a super little museum. Do a Google and take a look.
Best of luck in retirement - I can tell you from experience that you probably won't have time to write your book!