Are there any issues with the MDF bed warping?
MDF is a wood product and therefore it is not as absolutely straight as a heavy steel plate (which has been surface ground). It is expcted that MDF will stay straight within 1/64" to 1/32" over the bed length however, this variation does not affect its function. Of concern when printing is that the thickness of the bed remain constant (which it will, provided it is kept dry) so that the pressure applied at the point where the bed passes under the top roller does not vary. The advantage of the MDF bed is that itis far more economical to produce and much easier to move or transport because of its weight.

Why does the press not come with micrometer guages?
Most guages do not add much to the function of the press. While being costly to incorporate, equally good results can be achieved by using a small block of wood as a feele guage between the top roller and the bed. This method may require a bit of trial and error to establish the correct thickness of feeler guage, but once the correct feeler guage size is found, setting the correct height is quick and easy.