My Naza v1 with 4.02 seems fine on my DJI 450 stock with Gemfan props. Seemed very locked in even with GPS off. Set ceiling at 36 meters to try and worked well.
Most plastic not change signal.
Not unless black plastic, may contain carbon for color.
Of course carbon fiber blocks too.
And yes unit it's self plastic case.
Probably better results with GenAce packs. Use larger connectors and check solder joints. Progressive RC's ESR Meter is nice for checking internal resistance of pack and individual cells. It's good to use to monitor health of pack.
With a stepped prop reamer, Great Planes brand I think bought from Tower Hobby online.
It works very well.
Then check balance on Dubro Prop Balancer since I already had it.
GPS will work if sees enough satellights. Alt of course will work, and would assume alt reference is from home take off point, but an interesting question that maybe won't find answer for here.
Would not use cheap receivers to transmitters. Should count the clicks and set dead center for modes just in case drifts point or two.it is a fairly narrow area it has to be set for mode selection.