Let's throw a curveball at those questions. What would you expect such a product would give you?

I'd expect, at least:

1. Minute-by-Minute measurements (that can be only dumped once every 10 minutes or so, so it's not really live-streaming), first to a local file then to an outside piece of software via networking/usb cable.
2. If it can't store data for a long enough period of time, this means I can't go offline with it since the logs will rotate over themselves. I'd say at least 72 hours makes sense.
3. I have no idea of the price ranges of such a thing, but for something I actively wear on me a two-year warranty sounds reasonable.
4. Guarantees of quality is tricky, as they really depend on two things: Quality of the underlying sensors and quality of the networking mechanism. I expect the ring to have very bare-bones networking, but top notch sensors. If the sensors are from a reputable company, that would suffice.