Best approach for game sound engine on RaspberryPI in OpenMaxIL

I am writing a sound engine for my game. I want it to be able to play several static and streaming voices.
I want to be able to set the voice volume, pitch and channel volume matrix.
My approach is to create a combination of audio_render, audio_decode and audio_mixer components, connect them with tunnels and supply with wave buffers.
Can somebody help me with the following please?

  1. Is it the correct approach to allocate all those components for every voice? I plan to allocate them only when the voice is really playing (I measured and I can only allocate around one hundred of them at once).
  2. How can I change the pitch of the sound in a realtime (eg. when sound is already playing).
  3. I want to be able to loop static voices. I tried to submit buffer again in EmptyBufferDone callback but it caused hardware error. Is there a way to play one buffer several times without much effort (without allocating a thread to watch when buffer playback is completed)?