- Linux or FreeBSD no questions
- LUKS / GELI encrypted partition
- For Internet connection still better use tethering or CradlePoint
- Dont use RPi as your "center", I used hundreds of them for different projects and reliability and performance is a disaster. Only for narrow-tasked embedded applications. Build cheap, but real PC with Linux. Hell, even Atom-based tiny box will offer 100x time more flexibility then Pi with just a little higher power requirements. If you still set at Pi, consider TinkerBoard or BeagleBone as alternative.
I've installed a core node on an HP netbook under Ubuntu. Tethering is not really an option, the daily cost of synchronising the Blockchain makes it uneconomic.
I decided the Tinkerboard was a better option than the Pi for a comms centre in the van. I'd use that too retrieve videos to play on a TV as well as website maintenance and service of a 3rd Bitcoin node. It all needs to be 12 volt of course.
I've downloaded Wireshark, and I've got an eBook on it, and I hope that this will let me understand the problems of WiFi communications.