I do not have an Android device available until Tuesday so I cannot test the Android black screen issue yet.
However, the second issue you describe has probably something todo with the MultiResolutionImage: instead of anchors.centerIn: parent in the MultiResolutionImage, please use the following:
x: parent.width/2-width/2 y: parent.height/2-height/2
This is a bug in MultiResolutionImage which we will try to fix in the next versions. For a final release of a game, prefer to use SingleSpriteFromFile as it is more efficient though and TexturePacker can do the scaling to different resolutions automatically.