I don't have much to add about dithering, I just needed to get my post count up so I can PM someone.
Myself I like to keep things as 32-bit floats or higher when its possible.
Noise bursts can happen from a few possible causes: 1. Sample buffers weren't zero'd before mixing waveforms onto them. 2. Accessed wrong memory. 3. Most often, maybe, all the time, an IIR filter went outside its safe ranges and went unstable, these filters become "broken" because they fee...