Should I connect "line" to "line" and "neutral" to "neutral" on my power supply
In the case of "German" type plug you can never be sure which way the plug is inserted. This implies that your electrical mains is not built to distinguish between Live and Neutral, in other words the Neutral is connected to ground somewhere before it enters your house. As long as your device isn't relying on Neutral being uncharged at no-load conditions, it should not matter how you connect L and N.