Can I setup many NWC to use it as a mini Uncle Jim for family and friends as I could use for different uses?

Yes, but don't push it too hard. Is still early phase and the NWC server is in a continuous improvement.

Why is LDK better than LND in this scenario?

The comparison doesn't say is "much better". It only point out that is faster using it in slow networks and also uses less space on the device.