Is there any analytics support in this system for us to track where leads have come from ?

This can be built into the lead ‘source’ field.  You can give us as many sources as you like and we will add to the drop down.

Then there are standard reports which report on lead source.  Also, the standard campaigns module will allow you to add marketing campaigns like “Winter special offer” or “Xmas email campaign” and then log leads against those campaigns to give you an idea of ROI.