Understanding the wiring of 2-Pole Quad Circuit Breakers
Your understanding is correct EXCEPT you cannot put a 15A or 20A receptacle on a 30A breaker.  The 30A circuit must be wired to an outlet that is designed for 30A.  This would be a NEMA 6-30 if you don't need the neutral, or a NEMA 14-30 if you do (or the NEMA L-series locking equivalents).



There are devices factory-wired for these plug types in America.  The most common example is dryers on a NEMA 14-30 plug, but also welders, electric car chargers, and some shop machinery also use the NEMA 6 or NEMA 14 series plugs sometimes.