on the confirm page, the following code is used to create the iframe:
<iframe id="paypal-advanced-iframe" width="100%" height="500" frameborder="0" allowtransparency="true" scrolling="no" src="webassist/ecart/checkout/ppadvframe.php"></iframe>
you can change scrolling="no" to scrolling="yes" to allow for scroll bars, or edit the width and height settings.
for expiration date, you are missing the point. There is not a way to validate the expiration date. to determine if it is correct, it must be passed to the bank, at that point the transaction is being processed. I it is wrong, the transaction fails, if it is right, the transaction passes.