I had trouble getting a Dahua camera to take a 192.168.0.X address (192.168.1.X worked fine), but this was years ago and solved with a firmware update. I've had many Dahua cameras since then without issues.
It is true that you can't find firmware for some Dahua cameras. Specifically Chinese region models that have been hacked to English. I've heard of them losing their English language hack and reverting to Chinese, too, though it has never happened to me.
I can't say much about having
Blue Iris control the IR lights, except to say I don't know why anyone would want to. I've never had a camera that wasn't able to automatically control its own IR perfectly.