Does the Encore need a separate subwoofer?

No. It has two integrated subwoofers with adjustable bass levels, so the low end comes from the bar itself. That saves space and wiring but won't hit as hard as a dedicated powered sub.

Is the Dolby Atmos effect real surround sound?

It is virtual. The bar uses virtual height channels to add scale and depth, but there are no rear speakers or upward-firing drivers, so overhead effects are suggested rather than placed around you.

What is Auracast and how does it work here?

Auracast is a Bluetooth broadcast standard. The Encore can receive audio from Victrola Auracast sources and broadcast Bluetooth audio to compatible Auracast speakers for multi-room listening.

What connections does it have?

HDMI eARC, optical, USB-C and Bluetooth, plus Auracast in and out. HDMI eARC is the simplest hookup for a modern TV and carries Dolby Atmos.

The soundbar, a remote, an HDMI cable and a wall mounting kit, so you can set it up on a shelf or mount it without buying extra parts.

Will it improve dialogue on my TV?

A dedicated center channel keeps voices clear and upfront, which is the main reason to pick this over a plain 2-channel bar. It helps most at low volumes.