Bistropha cum clivibus pressis?

I see a clivis and a pressus (which has a subpunctis of itself). Anton Stingl notates it thus. The Laon notation shows me a clivis with an oriscus and unicus, which is also what Stingl notates.

Well, a subbipunctis would be two notes. In the Solesmes books, a subpunctis (or however many follow) are diamond-shaped, and you'd never see the notation as above from Stingl. In other words, they made the notes look like a climacus, even if it's not one, and in this case, the pressus minor and oriscus clivis are very similar/"identical." The good monks of Fontgombault, Triors, and Clear Creek (and the Schola Saint-Grégoire correctors for that matter) probably would have gone with your original description. (There's even a clivis with clivis, forming a pressus in the Laus in ecclesia level 1 book, ch. 4, without the two preceding puncta.)

(Depending on who you ask, perhaps) as I understand it, the neume which is flexus descends, but its basic form ascends (which would cover the salicus, scandicus, and porrectus; a descending neume like torculus which is flexus is such after first being resupinus).