Re: How to rotate a drawing so that I have 2 points on X axis?
Draw an auxiliary horizontal line of any length from the first point. Go to 'select' - 'select all', then to 'modify' - 'rotate'. Take as rotation center the first point, as reference point the second point, as target point the end of the auxiliary line.
You also can use the plugin 'align' (under plugins), in a similar manner, with an auxiliary line. Or find a more elegant way.