To respond to Hoverman's question, it is a known problem that some combined DVD/CD drives cannot read home-burned discs. Also, they're usually more choosy if you're using RW disks. With experimentation, you may find that your LG drive will read some brands but not others.
I think the answer to alcudia's question is that you probably can't add more images later. But it will depend on your recording/burning software rather than the disk format, because when you're making a slide show to play on your standalone DVD player the burning software also automatically places other software, indexes, etc. onto the disk to enable the standalone player to read it.
I am using CD-R disks and have been advised NEVER to entrust valuable back-up data to CD-RW. I have concluded that my DVD drive is not capable of reading data added later. Thanks to all for your replies.
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