Q #1 - I can see a few ways projects enhance student learning... in allowing them choice in subject area you increase interest. Increase interest -increase (hopefully) performance. Also, you can provide a list of project/assessment choice that can better address learning styles and levels - so not every kid has to right a book report or make a poster - you can steer kids toward choosing the assessment that is right for him/her. And if they are working off the rubric for the assessment they'll be using, they should be able to aim and hit the grade they want. The whole project thing can help encourage depth over breadth, esp. important since standards driven instruction seems to discourage depth.