i would advise against sand in a qt tank. the importance of a QT tank, is for it to be a controlled enviroment, so the new fish has the most stress free system they can get. Stress free means prestine water. If you have sand, this can just increase the likely hood of high nitrate, which can and will have a negative impact on an already stressed fish if high enough. You can use some live rock but again not needed, as you would need to remove it to treat your tank. LR will just absorb most of the chemical that has been added, making it basically worthless.
QT tanks should also have smaller more frequent water changes performed to provide consisten water, with out any BIG changes in the chemistry. Keeping everything as steady as possible will help ensure that you may never need to dose the tank with any chemicals.
PVC tubes placed in random stacks, glued to each other of course, so they dont float away is what gives the fish hiding places. I wouldnt make anything to intricate because when you go to catch the fish you dont want them to hide in anything that would be to difficult for you to get them out of. The catching process should be done without the use of a net, to greatly reduce the amount of stress. If you induce to much stress, you have basically defeated the purpose of the acclimation and would besically need to start over. As this rarely happens, never say never.
QT is also a very good time to practice good feedings. when i say this i mean multiple types of food. This will help ensure good nutrition and will greatly cut down on disease and stress.
