It's common practice to rinse substrate before you add it.
Hardscape is just a short way of saying all the non-living stuff you put in your tank: substrate, driftwood, rocks, decorations, and so on. It's common practice to rinse substrate before you add it. If you have a clay-based substrate like Fluorite, rinsing can take an obnoxiously long time (To put into perspective: I poked holes in the bag and left it under running water for an hour, came back, and the water coming out of the bag was still brown. I don't know if I just had a possesed bag of Fluorite, but the point stands). You don't absolutely have to rinse substrate off, but it will limit cloudiness and dust. You can also put your substrate in on a slant to give the illusion of more depth in your tank, but that's optional. For your filter, heater, and air stones, follow your specific product instructions (it's usually super easy).