The round, yellow/orange egg on an orange tree sounds like a giant swallowtail, but the description you give of the caterpillar doesn't, so I assume it's some type of moth. Just in case, here's a picture of a giant swallowtail hatchling - Sherry

Any chance of an image? Sure would help us help you.

I've raised a number of EBST in enclosures, plastic jugs and re-purposed fish tanks, as well as watched a bunch out in the wild of my backyard: I've never seen any suspend upside down like the Monarchs do, so news to me! Mine always had a preference for suspending vertically, whether on a twig/branch or even directly to the aquarium side (!), but never the roof/top. I was so fortunate to be in the room when my second EBST started its pupation. Here are some stills from the video -- it took almost 4 minutes from the time the caterpillar skin started 'cracking/peeling back' to the time the skin was finally shed. I'll post a few more as a separate comment, in case Houzz limits me to four images.

Tent caterpillars are moderately sized caterpillars, or moth larvae, belonging to the genus Malacosoma in the family Lasiocampidae. Twenty-six species have been described, six of which occur in North America and the rest in Eurasia. Some species are considered to have subspecies as well. They are often considered pests due to their habit of defoliating trees. They are among the most social of all caterpillars and exhibit many noteworthy behaviors.