I laughed reading the bit about the night sky Henry - I remember doing pretty much that in some random bit of Iraqi desert. Just looked up, seeing more shooting stars than I have ever see, seeing the band of the milky way and just going.. "wow". I think in more remote areas of the US you can see that, but being from the giant floodlight which is the UK, that was a pretty unique moment.
I didn't do my first tour of Iraq until I was 26, I'd done 2 years in N Ireland by then though. Since 2004 I've done two tours of Iraq and three tours of Afghanistan (Brit tours being 6 to 7(ish) months long) - my current job means I spend 4 months a year out there for the foreseeable future. But it's what i'm paid for and I enjoy it, so no complaints here - I'd go away more.
I will offer the advice to not try to get him to talk about things though- he'll decide when, if and to whom he'll talk about things with. From experience, people thinking you need to "talk" actually just makes you NEED to punch them in the face