A lot of your questions are answered in this thread:
I've been looking at the same things. As far as I've been able to tell there is no civilian version of the Remington ACR. Maybe someday, or maybe Bushmaster will implement some of those changes/variations. Some are more appropriate for the civilian market than others. The Military version loses the ability for rapid barrel change/conversion for instance, so that would be most likely different on a civilian version (done for weight savings on the military level, would be a valuable feature to keep for the civilian weekend warriors or multi-purpose types).