Some assignments will include "extra credit" sections. These will enrich your understanding of the material, but deliberately will provide scant credit in proportion to the work required. Do them for what you'll learn beyond the basics, not the points, and don't even think about starting the extra credit portion until the main problems are complete.
The midterm and the final will both be open book/open notes. For practice exams, see previous offerings of the course, in particular for Autumn 2008 and Winter 2009. The mini-exercises are also good study material.
You can email all the TAs and the instructor at cse341-staff at cs.