Here's my first question:
In Lion, if you turn on Filevault, you can no longer modify the System Preferences/Security & Privacy/Require password... after sleep or screensaver. The value is forced to 'immediately' and changes are not saved. If you haven't turned on Filevault, this setting acts as expected.
Has anyone found a workaround?
It's not a security feature, in that you can set the screensaver not to come on for hours (or never), but it sure is annoying for those folks who reach over and wiggle the mouse when the screensaver comes on.
A postscript: my workaround is to change the setting and never close System Preferences. Dumb, but it works.