can a shower be hooked up to this faucet or does it need to be separate in addition to the hand shower

As this faucet is designed to provide only two water ways, one to the waterfall tub spout and the other one to the hand shower, if you want to add a rain shower to this set, you could replace the hand shower way with the rain shower. Or if you want to keep the hand shower, then the rain shower need to be installed as an independent system.