Some study of the Jabiru manual and this aircraft might be in order. The noise on the intercom is classic alternator regulator failure.
The engine response in the air is strange. The Bing carbs automatically compensate for altitude so using the fuel cock apart from being a non-standard and blunt tool should not be necessary. However you increased the rpm. Above 2800rpm the Jabiru is meant to run rich to ensure it does not over heat. Artificially leaning the mix with your blunt tool compromises that richening and may lead to cylinder head / valve issues - which are far from unknown in the Jabiru. The ignition is direct from the flywheel coils so unless they have got hot (again a known Jabiru problem area, there should be cooling tubes leading to them from the cooling shrouds) there should be no connection to the electrical generation issue, but they are easily tested