>2) my experience has shown that you can have invis and invis to undead at
>the same time, although the order is important. I think you need to cast
>invis first, then invis to undead. However, this was about 20
>levels ago, so things may have changed recently.

I have tried it recently with my enchanter, in both orders.
The person I am casting on always says whatever the second spell
was -- its icon is up and the first has disappeared.

This may be something they have changed.