To fix the grid problem, please update to QCAD 18.104.22.168 (see also changelog):
When a bitmap is inserted into QCAD, one pixel is scaled to equal 1 unit in the drawing by default. To change this, you need to change the scale factor of the image when you insert it (option toolbar while inserting) or later in the property editor.
Please post any further questions about QCAD Professional in the QCAD Professional forums. This forum is for the community edition of QCAD (QCAD 2.0).