Home is people and culture as much as a physical landscape. :-)

And yeah, I am quite sure Rabadash discovered how his plans were foiled, and by whom -- Aravis overhearing his conversation with his father, Cor racing to warn Lune -- because that kind of story gets out and around even if nobody in Archenland told it directly to their Calormene prisoners. I am equally sure he has a long memory. But Cor and Aravis are much less likely to cause random havoc than Corin is, and they're also less likely to miss implications hidden by courtly misdirection, so they're still the better choice of ambassadors.