可

1. 入美国国籍拿到美护照后，第一次出美国回中国，用中国护照可以吗？ - Yeah, provided your Chinese passport is valid/unexpired (do you know your Chinese passport will be cut off a corner when applying visa at a Chinese consulate?)

2. 理论上来说，拿到美护照后，以后都不回美国，应该是可以的吧？- Yeah, when returning to US, you are required by presenting US passort per law