Re: Cross country skiing - skating vs classic
The difficulty depends on your experience of sports; if you've done sports that involve balance, you shouldn't find it too difficult.
For example, I already skate my alpine skis a lot to get around the mountains (when it's flat or you need to move uphill a short way), so transitioning to 'skate' XC I found to be easy. If you roller skate, or have ice skated, you'll also find it a lot easier than most people. I slackline too, they all complement each other. If you can relate to any of this, you'll be fine.
It does involve more technique than you expect though, so it is worth getting lessons to avoid bedding in bad habits. Also, look out for SNS bindings (with two bars) which I'm reliably told are the best. I found it very hard to find information out online about it.
Have fun, it's a fantastic sport! It also makes you a much better alpine skier.