It is the preferred choice for Carrier, Trane, and Johnson Controls. With a GWP of 466, it is significantly more "future-proof" against EPA regulations than R32 (GWP 675), making it a long-term industry standard.

Only if it is A2L-certified. Most older machines have internal switches that can spark. For R454B, the U.S. market requires tools that are "intrinsically safe" to prevent any risk of ignition with A2L refrigerants.

Yes, but it’s very small (about 1.5°F). For most residential applications, it behaves like a near-azeotrope. However, for maximum efficiency and system stability, you should always charge it as a liquid from the tank.