I have two cockatiels and a parakeet. One female lutino and one pied x cinnamon male. They hated each other at first but now they are in love. The female even lets the male clean her head feather and vise versa. The male whistles and sings, I've even trained him to sing the adams family theme song and the Andy Griffith theme song. He also does kissing noises and says " dawns a good boy."
Cockatiels do give off a lot of dust but I bathe mine in the shower and that helps a lot with the dust control. Some birds like to be misted or even play on wet greens. It all depends on the birds personality.
Female cockatiels are much less noisy then the males.
+1 buy the biggest cage you can afford.
Swap out the toys in their cage to keep them entertained and give them out of the cage time and people time and they will be extremely rewarding.