I have officially ordered the birth and death certificates for Wilhelm. I am doing this with the understanding that these Queensland records may not be 100% accurate.
The "source image" would be the best to obtain. Not only is it cheaper and faster, but it will contain information that may not have been transcribed onto a certificate.
The 1876 marriage cert of Elizabeth Schmeider to Henry Damm
Will be useful to your research for the information about her birth.
Again, the source image is the best option.