: Pippin, in the streets of Minas Tirith is hailed as an Ernil-i-Pheriannath -- 'halflings' being known of in principle, but most people not having seen one even in cosmopolitan Minas T.
: I frankly don't believe there hadn't been a couple of Tooks per generation making it to the centre of the known world in their peregrinations (sorry!), but that's not inconsistent with 99% of the city being surprised to see one.

: I'm sure Elves and Dwarves were more well known to the Gondorians -- from songs and tales that give them more detail on them at the very least. I suspect an Elf or a Dwarf wouldn't have to be assumed to be a prince(ss) of their folk, if they were to be seen in the same circumstances.
: But would it be likely that Elves would ever walk openly in the lands of Men, or that Dwarves (especially after the Balrog's diaspora) might go around building bridges and keeps for Mannish clients?

I too have had problems with the Shire remaining unknown to the world, though Tolkien uses various ploys to make it plausible. But given the shy nature of Hobbits in general and that for amny of them a great adventure would be fishing in a boat or sneaking a peek at the Old Forest, it doesn't surprise me that no Hobbits were ever seen in Gondor prior to Pippin's arrival. As to his assumed rank, that was explained. It had to do (if memory serves) with Pippin's use of language when speaking with Denethor. He used a form reserved for immediate family or at least political equals (from the viewpoint of the Gondorians), and though Denethor was mildly amused by this, others assumed that Pippin must be at least a prince to speak in such a manner to the Steward. It seems that Pippin did little to squash this rumor once it had started. I'm not able to look up the exact passage right now, so if I'm off the mark please correct me.