New to Crusader Kings with a few questions.

Hi Guys, I saw a post relating to this game and having always loved medieval era history I immediately became very interested. I've never really played a grand strategy game (unless you consider the civilization games grand strategy?) and so I just had a few questions. Keeping in mind I have been watching lets play videos on youtube to try and wrap my head around this robust strategy game in the quickest amount of time possible.

Is there really a defined way to win the game? If not how do you judge your success after you've played a game?

How long does it take to play through a single game?

What advice would you wish someone gave you when you were starting that would have saved you a lot of frustration?

At what point does the multiplayer become viable for a noob? I love the idea of playing this game with other human players but have no illusions that I'm probably not ready to yet....

Please feel free to make any other comments, all input by players with more experience then myself (so pretty much everyone), is greatly appreciated.

Thanks and I look forward to hopefully becoming an active member of the community.