iOS managing compressed tracks playing at the same time

iOS managing compressed tracks playing at the same time

I am the Sound Designer for an iOS game and I am facing the problem of
optimizing space in MB for the sound I am creating. I do not have a lot of
space compared to the amount of sound I want to create for the game. A
typical sound scene will be composed of various layers, generally like
this:
Music
Background Ambiences
Cyclic Sound 1
Cyclic Sound 2
Sound Triggered by the User 1
Sound Triggered by the User 2
The obvious approach would be to compress everything in MP3 or AAC but as
far as I know only one track is processed by a dedicated hardware at the
same moment, the rest of the sound playing in compressed format are going
to eat CPU resources that the game engine is using. The game is not heavy
on CPU, it is not animated but mainly with static images, I know that I
should discuss this with the developer but he does not know a lot about
audio codec and quality, so I would like to meet him with something that
will not ruin the CPU and at the same time allow me to put a lot of
quality in the sound.
I would go like this:
Music -- mp3
Background Ambiences -- mp3
Cyclic Sound 1 -- mp3
Cyclic Sound 2 -- mp3
Sound Triggered by the User 1 -- Wav
Sound Triggered by the User 2 -- Wav
Do you think this solution is suitable from a developer perspective?