I would not change the type of the creatures from the material plane to Outsider or Native outsider as that has implications for HD, BAB, saves, etc... However, Banishment and Dismissal cast by someone from the, say, astral plane on a PC from the material plane would kick them back to their native plane, will save providing, of course. Not sure if that is exactly RAW, but the spells don't call for a creature of the Outsider type, they call for an Extraplanar Creature, and from the point of view of the astral plane, humans, dwarves, etc are very much extraplanar.
Creature type does not change when moving across planes. A humanoid will still be a humanoid if they travel to Hell.
Creatures that are on planes that they aren't native to gain the [Extraplanar] subtype. [Extraplanar] creatures are subject to Banishment effects. (You can banish a devil while its on the material plane, but you can not banish a devil if its already in Hell.)