The sap is clear, it has a really high water content.  I've been told that when you boil it down to get the syrup it could be up to a 40/1 ratio.  Length of tapping depends on the weather.  It has to get above freezing during the day and below at night.  It could be as much as 3-4 weeks or as little as 1.  Again this is my 1st year so I'm still learning.