Yes, this is the 750 SE. It does not require constant connection to the phone to work, but some features do require pairing the device to Bryton Active app. For example, to enable the navigation feature, you must first pair the device to the Bryton Active app. The user manual covers this and it's available for download at Bryton's website.
No, it does not need a connection to work. If you connect them to the phone you have extra functionality, which I lost I have never used. Yes SE corresponds to next gen.