It's for Halloween at my house (non-commercial).  I want to place about 6 speakers in my yard with the ability to mix sound effects flexibly to any speaker, based on triggered sensors and/or manual control.  So this is not a canned soundtrack, it's dynamically triggered, independently for each channel.  I can handle the sensor input, the manual input and the logic; it's the audio control I need some guidance on.

For sound I'd like to be able to play a given MP3 or WAV file on a given audio channel, independent of other audio channels.  So when a PIR sensor is triggered, I might start a cat yowl sound effect on channel 3 (speaker under the Maiten tree), then a few seconds later (while the cat continues to play), I might manually trigger rattling chains on channel 5 (speaker by the courtyard wall).  

Ideally, I would be able to mix multiple sounds on each output channel, and distribute an input sound among multiple outputs - for example playing a background ambience through all six speakers, with the the above triggered special effects mixed in as needed.  It would also be nice if I could dynamically and independently route the two input audio channels of a stereo MP3/WAV file to my choice of speakers, eg: play stereo rolling thunder with left channel going to speakers 1 & 4, right channel going to speakers 2 & 6.  One more desiderata: mixing in a microphone as one of the sources.

And I'd like to use a 5.1 or 7.1 USB soundcard for output so I can drive this with a laptop; if need be I'd drag down the main computer and use a PCIe or PCI board soundcard tho.

So - Can Minim handle this?  What 5.1 or 7.1 channel soundcards work with it?  Any suggestions?

Thanks!