Primes and Planars
Primes do not gain the extraplanar subtype when off of their native planes, even native outsiders born on the Prime Material Plane. As such, they are not at risk of being whisked to another plane by a spell crystal containing a summon monster or planar ally spell, or assailed by incessant questions from a spell crystal containing a contact other plane spell. In fact, primes are never targetted by spell crystals at all. They cannot be driven back to their home plane by the effects of banishment, dismissal, blasphemy, dictum, holy word, word of chaos, and similar spells, although they are still subject to any additional effects these spells may have. (And if they’re lost in the Abyss, low on supplies, chased by a horde of tanar’ri, with no idea how to get out, they may well wish they could be driven back home by one of those spells.)
Planars gain the extraplanar subtype when off of their native planes. They do not have a silver cord when travelling the planes via an astral projection spell. Planars can be targeted by spell crystals, and driven back to their native plane by the effects of banishment, dismissal, blasphemy, dictum, holy word, word of chaos, and similar spells. Finally, planars are always able to see the gates between planes, whether or not the gate is active. They do not gain any information about the gate, such as where it leads or how to activate it.