- 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.