That's not a fast trip for short-circuit; that's the thermal overload curve protecting the motor windings.
Breaking capacity — what 100 kA means at 400 V
For a panel fed from a transformer with high fault potential, that rating keeps the arc flash contained within the breaker.
Mounting position is any — vertical, horizontal, upside-down — which simplifies panel layout when you're stacking breakers in a tight enclosure. Screw terminals accept 2×(0.5…1.5 mm²) or 2×(0.75…2.5 mm²) solid or stranded, so common motor feeder cables land without adapters. Clearance requirements: 20 mm upwards, 20 mm downwards, 9 mm at the sides, zero forwards and backwards. That means it can sit flush against a backplate or gland plate without derating.