The problem is that the NRF devices are not a system, they are RF transceivers only. You will need a processor at both the remote and base ends.
Although not officially supported by Cayenne, we have been able to get the ESP8266 modules to work as a system, and to sleep to conserve power, you just need a battery that can handle 80mA bursts. The CR2032 can't.
The MKT1000 is also a full system and includes the circuitry to run off and charge a lithium ion or polymer cell.
There are howtos in the forum to get both of those working, so you'll be just fine without much microcontroller or programming knowledge. To monitor the supply voltage, you can use the Ain pin on the ESPs or any analog on the MKTs connected to the supply (3.3V or less).
I currently see no advantage of using the NRF units now the ESP and MKT devices are available.