The 'Adjust Audio track volume by' should adjust any audio including RealDrums and RealTracks. As far as Midi, the volume is determined in the style as programmed. Raising the Master (ctrl alt D) or part volume should reflect in the Render. Be sure to save with patches (Alt F2) and have Save settings for Volume checked. As a last resort you could try Normalizing in Opts|Prefs|Arrange but you would be overriding the mix BIAB has put for the instruments.

Rachael