A:AnswerYES!!! I don't have a C wire and I was worried about this too. But it just steals a trickle of power from the HVAC line which keeps it going just fine. You don't need a C wire or a pricey electrician.
A:AnswerYou won't get an alert if someone changes the setting manually while you're away. However, you can control with your iPhone when away from home. You can also set it automatically to Eco mode when you leave home, based on the location of your iPhone.