What is the difference between the ambiguous (yin yang symbol), question mark, and "complicated" indications on my StrateGene Report?

The ambiguous (yin yang) symbol means that the particular SNP is substrate-dependent.  This means it can process some chemical compounds quickly, other compounds with different geometries will be processed more slowly and other compounds will be processed by the variant enzyme at the same rate as someone without the mutation.  So the speed fluctuates depending on the compound being processed.

The question mark symbol means that the impact (speed) of that particular SNP is unknown or controversial, or there is not enough science to point to any adequate implications.

The orange and purple striped gene on the pathway known as "complicated" is referring to a gene that has SNPs with ambiguous, unknown, or mixed speeds, which causes there to be no single overall impact on the gene.