I did notice 2 telemetry kits on sell on DIYDrones store, the Xbee Telemetry Kit at $150 and 3DR RadioTelemetry Kit-915 Mhz at $74.99. Which one is compatible with APM2 (purple)? If both are compatible, do you have any suggestions? Are both 2-way as I believe. My actual FPV setup is uplink TX at 2.4 GHz (Spektrum) and video downlink at 900Mhz. Should I use a 433Mhz telemetry kit or 2.4GHz?
Go for 3DR radio telemetry at 433MHz, longer range than Xbee and you stay away from your video transmission frequency.