I've managed to work out most of the functions but there's a couple I need help with:
1. In Theatre mode 2 keys are always visible- "AudIn" and "VidOut". What are these for?
2. In Theatre personalisation it has a setup key for "PIP". What is "PIP"?
I'd apprecaite any help with these queries together with any tips on how best to configure the Theatre mode.
Thanks in advance.

"Picture In Picture"

Some device (usually the TV, but sometimes a VCR or other device upstream of the TV) combines the output from two tuners (or other video sources) so that one appears in a small box near a corner of the other.

It's normally used to put a commercial (that interrupted the show you want to watch) in the small box, while you watch a little of something else, but get to see when commercial ends.

Sorry, I know nothing about the 9990 or the rest of your question.

Thanks johnsfine
Anybody on the other points?