Hi @hydrocynus,
We recently introduced the BLE feature that allows you to connect to Reach using Bluetooth on your phone. At the moment, it’s in Beta. But you may try this out if you don’t plan to do any significant work with the receiver. Please check this topic for more info.
Reach should work with Microsurvey FieldGenius. Have you tried following the configuration steps from our guide?
I can’t say the exact number, but the RTCM3 messages are lightweight. I took a random log on my computer from CORS and its size is 2.1 MB. It was recorded for 2 hours.