Can Spy Apps be installed remotely?

No, you would need access to the device to install the app and track the device remotely from a website.

How to spy on a smartphone remotely?

You would need to install an app on the target phone that you want to spy. Only then you can track the device remotely. TrackMyPhones has remote-tracking apps. Spy Call Recorder, Spy Audio Recorder are few of them.

How to record calls and listen to it remotely?

You would need to install an app on the target phone that you want to record calls. The app will then record all the calls and upload them to the website where you can login and listen to those call records. TrackMyPhones’ Spy Call Recorder is one such app that helps you listen to calls remotely.