Unfortunately, I've not been to Nami on Christmas day. However, I believe if u reach the island by 10am or earlier, it should not be crowded. That's the time I arrived and it was fantastic till the crowd swarmed the island. Hope this helps.

I would say no. Because of global warming, there's rarely snow in most parts of Korea; even in the most high season places. It rarely snow in recent years.

It’s easiest and convenient to take their bus shuttle service that picks you up from central areas and drops you off at the ferry entrance. tripadvisor does not allow me to post the link. But you can google “how to get to nami island” and check their website at namisum Or book a day tour with Klook or Trazy to explore with other attractions around that Gapyeong area.

U can take photo or video, there no restrictions that i am aware of. You can check their website

Sorry, i can answer your question exactly because i visited Nami island with travel agent so they prepare all of our stuff. Maybe you can find out at klook or other provider, thank you

If you are driving yourself you can buy entrance tickets when you arrive at these destinations. However if you want to go with a guide/driver, you should book a week or two in advance, to make sure you don't miss out.

Not sure if there is storage for baggage, before and after ferry. But there are many restaurants for lunch bedore ferry and on arrival of island., and you may try to ask the restaurant people for help to hold your baggage for you.