do you lose ranking points if you dont play a day?
Yes, ratings erode a tiny bit each day you don't play. You can find all the details about the ratings here: http://forum.shuffleit.nl/index.php?topic=1679.0
But the short summary is: there are three things that contribute to your overall level, and the most important two represent your "true skill" and "variance". True skill goes up or down when you play based on whether you won or lost, and proportionally to the skill difference between players (win against more skilled players for bigger increases in skill). Variance goes down by playing games, and up slightly if you don't play, representing your ability deteriorating over time if you stop playing, and to prevent inactive players sitting on a top spot forever.
thank you very helpful information!!