Thanks for sharing some helpful things you found to answer your question. We have also had a discussion about this a while back and @ianlyons managed to get it working as he mentions here
Otherwise I also managed to find this image that shows you how to connect minimOSD to your pixhawk:
Hopefully that will help, but as for RSSI I am not sure if its enabled on a pin yet on the pixhawk. But here is a guide on how to do it for the APM board if your receiver supports RSSI
- Provide RSSI from FrSky receiver to APM.
- Select the input pin with the RSSI_PIN parameter.
- However some of receivers such as FrSky D8R-XP output 0 – 3.3 V.
- For that reason I’ve added new parameter: RSSI_RANGE.
- This was also a requested issue previously: APM RSSI 3.3V input (feature request) · Issue #648 · ArduPilot/ardupilot · GitHub
- When the RSSI_RANGE parameter is set to your radio’s maximum RSSI voltage the RSSI rxrssi is shown in the range 0-100.
- The ability to set the RSSI_RANGE parameter has been added to Mission Planner in the Full Parameter List:
For more information you can view it on the arducopter wiki - http://copter.ardupilot.com/wiki/common-rssi-received-signal-strength-indication/