Help for BMS 4550 FRD AND ZMA files

You will need to put them together to measure.

The BMS should be able to keep up. Dayton do not have horn specs on their site that I can see. They say use it to 800Hz but judging by the size, perhaps a little higher than that.
 
UMIK1 is a USB mic. This takes extra steps because USB mics are not designed for crossover work.

You will need to use the acoustic reference option in REW. This means you use a separate speaker to send timing signals.
 
You would connect an extra speaker to the other output channel. It's output acts as a timing reference so you leave it in one place relative to your mic, while measuring different parts of your speaker.

According to the author of REW it may be better not to use a USB mic in a reflective environment.