WTG with the inaugural sail!!!

Trap length sounds correct. Just use the upper rung until you get more comfortable with it. Dog bones are great for single handing because it is one less adjustment requiring your most limited resource, hands. With practice, your technique will get better and you'll learn when it is preferred to use the lower rung based on conditions, length of leg, and point of sail.

I also feel that a good pair of skiff boots give added traction for moving on/off the trap but many will race bare footed also.

You will not be the same after flying the chute, especially single handed. Just remember to bear away/down when she heats up. The beginner's tendency is to head up. Get an experienced F16/F18/N20 crew/skipper out with you in the beginning to shorten the learning curve. Or conversely, crew on their boat. The other advice with the chute is that you have to keep up your speed when gybing once the winds get into the teens. That means you have to fully commit and not come around slowly.