Does the 5.1.2 layout mean real rear speakers?

No. It is a single bar with a subwoofer. The .2 refers to upward-firing height channels, and the surround channels are virtualized from the bar rather than coming from separate rear speakers.

Will it decode Dolby Atmos?

A 5.1.2 configuration is built for object-based formats like Dolby Atmos and DTS:X, but confirm the supported codecs on the product before buying, since the listed specs only state the channel layout.

What is the subwoofer connection?

The specs list a subwoofer but not whether it is wired or wireless. Check the connection type before you plan placement, since a wired sub limits where it can sit.

Can I stream from my phone?

Yes. Bluetooth 5.1 is built in, so you can pair a phone, tablet or computer and play audio wirelessly.

How does it compare with a 5.1 bar?

The extra height channels are the main difference. A 5.1 bar gives you surround and bass; this one adds overhead effects, which pay off most with Atmos and DTS:X movies.