Edge loops and triangles in female game meshes?

I’m studying the edgeloop tutorials from here and CGsociety, and recently I started turning to game models for studying the female figure.

When I opened up the Second Life avatar model, I was greeted with a mess of triangles and poles- but I’ve seen this avatar in game, people modify the morph targets with sliders in game and actually manage to make it look good.

But due to all the triangles, I have no clue how to study this, or other similar game models ( http://secondlife.com/community/avatar.php look at the female mesh in the zip file ).

How do triangles effect animation for female game models? What is their purpose, what can I learn from the game models that use them?

P.S. - If anyone has a good resource on studying topology for the female body, please let me know!