Hi @flyingbirds,
Yes. Enpass Assistant lets you do the autofill using browser extension and basic functions like searching and viewing items, edit existing items, copying information, generating passwords,etc. Refer to this link for more information.
Yes, Enpass must be running in the background because the extension fetches data from the App. Enpass is an offline password manager and it does not store any of our user's information on its server hence extension can not fetch any auto-fill data without the installed application.
NOTE: You can set the Enpass app to auto-run on system startup and keep it always running in the system tray or menu bar.
No, It is not an Electron app. Enpass uses a cross-platform QT/C++ framework that compiles everything to native code. Enpass is designed to run in the background for a long time and there will be no performance hit.