Your concernes are well laid out but nothing that boeing wouldnt have checked as they have done quite well so far with integration and systems . Most of the major electrical systems have been running for close to a year now and we havent heard much issues with them , boeing hasnt warned of any nor have the suppliers . issues which were problematic have been Id’d and either corrected or done away with for the sake of simplicity and cost . FCS is also flying with the 777 and laws being verified . I havent heard of avionics and system functioning trouble other then the complex integration of doing it in the first few jets ! Most of the trouble being seen now is in putting this together in the given time overall the systems are performing well seperately .