As your client is a Mac fan he will have a Mac running itunes software. This software stores all the music that he puts on his ipod. itunes is probably the best and easiest to use mp3 software - the connection between mac and ipod is seamless.
When you plug the ipod into a mac it automatically updates the music you have on your mac and puts it in the ipod. This is done by Firewire (also known as 1394 or ilink) and is very fast (8 minutes to copy 100 albums), it also charges the ipod on the same cable.
Therefore you need to tell your client he needs to control the itunes program on his Mac where the music originated, not on his ipod which is for use outside the house.
There is software to let you automate itunes playlists (and your Mac friendly client could probably even write an applescript himself). There is even software to control itunes from the mac calendar program (ical) for example. All of this software is free with the mac or a free download.
However if he wants to select the music he will need to remote control the Mac. This is just like remote controlling any PC. You can use any infrared mouse/trackpad to control itunes remotely. All Mac mouse and keyboard connections are USB.
If you can generate RS232 commands from your automation system you can get RS232 to USB converters and this could possibly control the Mac though this may not work as well and requires experimentation.
Getting video out of a Mac is easy. Just get a PCI card for a desktop model and all Powerbooks have Svideo out as standard. All imacs have video out built in either VGA or svideo depending on the model.
There is also some basic home automation software for the Mac if you want it to be the master control. I'm not sure how good (or recent) any of this software is, however given that Macs are now essentially unix machines there are more possibilities along that route also.
The only way to send ipod sound into your system is to put an audio sender on the headphone ouput of the ipod - this is inelegant and not really the Macintosh way...
Those links in full:
apple.com - tech info on macs, itunes and ipod shed.com mousehouse.net msystems.com
