I tried to find some examples of System Events parsing a plist file..
[...]
How do I I search for "creation" and return the string value?
How to I search for "happy" and return "false"?
tell application "System Events"
tell contents of property list file "/path/to/your.plist"
{value of property list item "creation", value of property list
item "happy"}
end tell
end tell
--> {"2007:06:12 20:13:52", false}