Cosine similarity is defined as
$\frac{A\cdot B}{|A||B|}$
Now, if you multiply it by $|B|$, so that you have
$\frac{A \cdot B}{|A|}$,
what is the name for this?
Could this be considered a principal component?
and what kind of properties / interpretation would it have,
particularly in comparison to cosine distance or Euclidean distance?
It's a length of the projection (multiplied by sign of $\cos$) of the vector $B$ on the vector $A$.