Well folks, as I said in the last log, I had a few goals in mind. I ran into some trouble with the example code, and so I turned to Github to contact the developer. He responded within 18 hours to alert me that the issue I was experiencing was a known bug that was fixed in the most recent version. I downloaded the new one and tried it.
It worked. The RPi was connected to the nRF24L01 radio which could talk to another Arduino/nRF module running example web server code. From back on the Pi, the software adds a soft NIC to the Pi and then a static route is added. The RF radios are on the 10. network and the pi is on my 192. network, so this allows me to ping the remote Arduino at 10.10.2.4 IP from the Pi's terminal. On my home router I also added a static route for the 10.10.2.0 network via the IP of my Pi 192.168.1.149. I also made a DHCP reservation for the Pi and set the address to be static on the Pi's etc/network/interfaces file. Adding this static route on the LAN means I can ping the Arduino from any machine on my LAN just like it was another WiFi device. That was pretty cool.
I was starting to look at why it was so slow (only 50% ICMP success usually) and so I started poking around the soft NIC stuff and broke something. I'm currently waiting on my Pi's SD card to be written with a new install of Raspbian. We'll try that again and be more careful next time. All part of the process. Live and learn :)