The first question in the title might be too much in general.
The cases I'd like to understand in practice are quotients (as algebraic varieties) of $GL(n,\mathbb{C})$GL(n,C) (or $SL(n,\mathbb{C})$SL(n,C) if you prefer) by finite subgroups.
Is Is there anything I can say about such athe quotient (set of cosets)?
The simplestbabiest case would be the standard representationrep of the dihedral/symmetric group $S_3$.
What What is $GL(2,\mathbb{C})/S_3$ (or$GL(2,C)/S_3$? Or $SL(2,\mathbb{C})/S_3$$SL(2,C)/S_3$ if it makes things easier)?
Essentially what I'm trying to do is embed a finite group in a special group (in the technical sense) and understanding what is the quotient is.
Any ideas or references?