You can normally run 1 telemetry module without needing the sbus hub.. On My brother's he has the electric temp sensor module plugged in to his receiver and taped to his motor to monitor temps mid-run. Unless he decides to run another telemetry module the hub isn't needed. The module's are sold separately.

Voltage is included from the receiver itself, but only tells you what voltage your receiver is getting from your ESC which is typically 6.0 or 7.4 volts in high voltage modes.