missing device

[outdooraudioape]

I already have the following:
1. 12V HEAVY DUTY MARINE BATTERY
2. 12V PA AMP with a RCA-style input jack available labelled AUX/CD.
3. 2 OUTDOOR SPEAKERS
4. A means to transfer digital audio files to a memory card (my PC).

What I need:

1. A device that I can plug in to the PA AMP that will accept my memory card and enable me to play any audio file that is on the card on the outdoor system.
2. A device that can activate all of the above instantly, such as, for example, two infrared sensors or motion detectors plus an intermediate device that will "trip" when the sensors sense motion, and turn on the PA amp, and turn it off after 1 minute or so. I do not want the AMP to be on otherwise, unless I manually override the trip mechanism.

Obviously I don't want to run any wires from the house to the outside Amp and speakers location.


Any suggestions, anybody? Thanks!