Should I turn the big switch from the Time Machine preferences to OFF?
Yes. TimeMachineEditor handles the scheduling itself and has its own ON / OFF switch (which behaves very much like the one from Time Machine).
Do I need to keep TimeMachineEditor running all the time?
No. You just need to use TimeMachineEditor when you want to change the settings.
What about backups when waking up from sleep?
When using the “Calendar Intervals” mode, Time Machine backs up on wake only if the computer was asleep at schedule time. When using the “Interval” mode, this behavior may not work, this is due to a bug in Mac OS X (radar 4058640). You can workaround this by using the “Calendar Intervals” mode instead and adding as many “Daily” entries as necessary.
How do I uninstall TimeMachineEditor?
That’s really easy. You’ll probably want to use TimeMachineEditor one last time to turn it OFF, you can then trash the application.
If you were using versions prior to 2.5, you may need to use an older version to revert system settings to their defaults.