Is it ideal to let the phone die completely before charging it to keep it at peak performance? I just got my X

In addition to the information provided, letting the battery die is bad for it. You should not allow it to completely die, to where the iPhone will shut down. Repeatedly doing this can damage the battery.

Not at all. Charge whenever you like or whenever it's convenient. You can also not overcharge it.

No. You can charge it anytime that is convenient for you and for as long as convenient. There is no benefit in letting it discharge and you cannot over charge it.