Price doesnt update when size selected

Hello,

1) I have a variable size option for a product and its respective price value. But when i select the size, the price changes, but when i add the quantities, the price remains the same.

ex: Size M $2 and if i select quantity 5, i dont see $10 until i get to the checkout page. Can the Shop page be dynamic to reflect real time price change.

2) What does hb theme recommend for a PCI compliant plugin to securly process credit card charges.

Thanks.