I want to use my autocad files(.dwg) and my field files (.crd), and want to know if they are compatible with qgis.
Simple answer is you need to convert these formats to DXF format first. After that it can be possible to load into QGIS - as far as it follows standards and preferably older versions of these standards.
But there are many issues related to it coming from differences between CAD formats and GIS formats:
QGIS doesn't care about styles / colours in DXF and is generally able to import only points, lines and polygons (and somehow a bit other objects if you are lucky)
QGIS doesn't care about layers in DXF and elevation data - by importing the file you simply loose all that information