It’s definitely a dosage thing, but cats don’t really have any brakes when it comes to chewing on shit. So they will chew anything that looks like grass, which can be dangerous when you have toxic succulents that have large leaves.
I second the drainage comment, hopefully it does have holes at the bottom. Otherwise instead of succulents I would recommend OP to put in “air plants” (Tillandsia) as they don’t need soil and draw moisture from the air.
In this case by hitting create post, it triggers the permissions for mic/camera because it tries to activate them.
As to why, it’s probably because they want you to create videos, so it defaults to that when trying to create a post. And then in there, you can go for a text post instead. But I don’t use Instagram so I don’t know if anyone who does can confirm that.