Neptune is the far most planet from the sun and hence it is even the coldest of all planets.Just like all other planets even neptune has rings which are made up of 30% dust and some rother rocky planets.Some rings have upto 70% dust.The rings of Neptune are quite hard to spot because of the amount of sunlight reaching it is really less.
Though,it is very much true that Pluto and Neptune cross each others orbit,but no they can't collide cause because Pluto's orbit takes it much higher above the Sun's orbital plane.So when Pluto is at the same point as Neptune's orbit is, it is actually much higher up than Neptune.
Deep down inside Neptune, the planet might have an actual solid surface. At the very core of the gas/ice giant is thought to be a region of rock with roughly the mass of the Earth. However,there is simply no way one could stand on the "surface of Neptune".