Glad i could Help with installing MissionPlanner.
As for your navio 2 issue, i’d strongly recommend opening your own thread in the copter category or maybe also here under “mission planner”. I guess there are more talented people there, able to help. Unfortunately I’m not very experienced in this field.
Anyway, as far as I know you should be able to connect your raspberry ground station with an ethernet cable to your antenna. Your navio2 would need to have an corresponding antenna with the same frequency. (2.4Ghz I’m guessing?!)
You’d need to connect to your navio2 flightcomputer in mission planner via port eth0.
I’m not sure if this would work out easily however.
Edit: by the way. Don’t expect to much in respect to speed gain just by upgrading your ram. In the end the bottleneck still will be the processor. It will never be as fast as on a “real” computer.
By the way. Maybe this helps? Navio 2 Connection Problem