#1 You can use something like this: [If,([IExists,Tool:UV Map: Delete UV]&&[IsEnabled,Tool:UV Map: Delete UV]),
[Note,"This model has UVs"]
]
The IExists checks that there is actually a Delete UV button, as some 3D models don't have it (for example, zspheres). If it's there and enabled it means there are UVs (as they can be deleted).
#2 Sometimes you can wrap [IKeyPress,13, /*command here*/] around the button press but this only works if pressing enter on the keyboard gets rid of the dialog and continues with the action. For example, using it with Tool>Subtool>Delete won't work because pressing enter cancels the action.