While modifying cart module layout, I found that to get the result I wanted - no "float: right" cart link (shouldn't this be handled by class+css?), no "Total:" text etc, I have to modify core virtuemart files - "mod_virtuemart_cart.php" and "cart.php" controller for proper AJAX update (including view logic in controller is, well, bad practice).
While not a bug, this is not a feature either, as cart module is one of the most important modules in front-end and should be easily customisable.