Hugh
I am 59 and I don't feel stable on a recumbent 2 wheeler's when I first tried them out. Commercial bikes were tested before becoming familiar with this site. And that was 10 years ago at 49. However I loved the feel of the recumbent trikes. Never had the problem with an upwrong. But I suspect it was old habit and disorientation. That's why I attempted to focus on various trikes. With my knees and Carpal tunnel the trikes were the only way to go. Thus my focus to build them.

Unfortunately the Lungs gave up on me despite my clean living of not smoking and loosing weight for Diabetes. So I am only able to observe and enjoy your builds and advise as I see the opportunity.
As to learning curb it is up to you. I would consider elbow, knee pads, and decent helmet if you are unstable to prevent injury. But it does look like a fine ride regardless of my lack of desire to try it.