Thanks, Thomas. For diffusion I've been using a sheet of Yupo laid on top of the enlarging paper during part of the exposure. Yupo is a synthetic paper that is completely homogenous, so you don't have to worry about texture. You can move the Yupo sheet relative to the paper to get different degrees of diffusion, but if you move it too far, it basically adds overall fog. There are many different methods to achieve diffusion: soft focus filters, nylon stocking, mesh screens...etc.

Regards,
Daniel