Yes, it's exactly as I know it from Germany. <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" /> More or less (the biscuits aren't that common in the area of Germany where I live, and the thing with the 13th is unknown to me so far). At least as far as I can see and judge it fom your descriptions.
Children have rhymes concerning the number of candles you burn begin to burn on each Advent :
First Advent -> 1 candle
Second Advent -> two of them
Third Advent -> three
Fourth Advent -> four (and normally it's Christmas then, if I remember corrdctly <img src="/ubbthreads/images/graemlins/smile.gif" alt="" /> )
Another Children's Rhyme goes like this :
"Und wenn die fünfte Kerze brennt,
dann hast du Weihnachten verpennt."
Which means : When the fifth candle burns, you've overslept Christmas ... <img src="/ubbthreads/images/graemlins/biggrin.gif" alt="" />
(Hope I've spelled it correctly.)