The planet would have burned to a crisp a long time before it even touched the sun. A waft of residual gases would maybe get close enough, which does exactly nothing.
It's the equivalent of tossing a single grain of hail into an active volcano.
Uh, yes. Absolutely. The corona of the sun alone is about 5 million km thick and has temperatures of >1 million degrees C.
Crossing that distance takes about 0.3 light minutes. For a planet with a somewhat large mass traveling at a fraction of that (average travel speed of celestial objects is around 1000-10000 km/min, depending on its mass), it would take between 83 and 833 hours (3.5-35 days).
For reference, the distance from earth to moon is about 400000km (and takes a rocket 3 days to traverse), so the sun's radius is about 12x that. Just put things into perspective.
Silicon vaporizes at 3650°C, iron at 3500°C. A couple days at a million degrees? Yeah it's vaporized alright.