Hi Robert, thanks for sharing your experience with us. I'm planning to self-publish my first book in May, so it's great to get all your wisdom and advice! Thoughts on your cover drafts:
1. For the second cover, could you use a tank, a motorcycle or other land vehicle? That would fit in with your other books. It sounds like you need another one as well to go on a fourth book.
2. Are you planning to change the title for 'Cage the Chinese Dragon'? The others are all called 'The [Something] Conspiracy', which I think works well. Can you use the same structure for the first book? If not, maybe don't use that for the other two, because then the first doesn't really fit in. You could also have variations, e.g. 'The [Something] Affair', 'The [Something] Cover Up' and so on.
The new covers look more modern and I definitely can see the genre from them. I would guess they are James Patterson style thrillers. If that's what you were going for, I think you nailed it. I like the colours and to me they strike the right tone.