no idea what that bin might be like, but for the mterials:

the straw, leaves and sawdust are fine bedding material, if kept wet ... the coffee alone is relatively useless because it doesn't hold water well, and takes forever to become microbially active .... the grass clippings [high nitrogen] need to be well mixed sparingly with the carbons [bedding] so that they don't heat up, which presents the only danger of 'killing' your worms

the best bet would be to shred up the straw and leaves together if you can, even by laying them on the ground and working'em over well with a lawn mower ... mix in some sawdust, wet it well, mix in some grass and coffee and give it a week being kept wet and there should be enough active decomposition to keep the worms happy

Bill