Write to support@windowbird.app — a real person reads it, usually answering within two business days.
The app version (Settings → the version line at the bottom), your phone model, and what you expected to happen. In Settings there is Send feedback, which attaches the app version, the platform and the in-app log to the message — it tells you exactly what is being sent before it goes.
The older one. It needs a camera and a charger, nothing more — that is the whole point.
Yes. Press the lens against the glass to remove reflections; the app's setup step shows you how and takes a test shot.
The watching phone stays on the charger, keeps a charge limit, pauses when it gets warm and sleeps from dusk to dawn. All of that is shown on its screen.
Purchases are handled by the store, so refunds are requested there: on Android through Google Play (Order history → Report a problem), on iOS through Apple (reportaproblem.apple.com). If a refund is refused and you believe the app is at fault, write to us anyway — we would rather refund you than argue.
What the app does with data is written out in full on the privacy page.