Admin,
Option #2 worked the best.
I am using a stand-alone checkout page (no sidebars). Customers are taken to the checkout page once they click "Buy Now".
In case this might help someone else looking for a similar fix:
I widgetized a section of my header (where I want the cart link, since I'm not using sidebars on my separate checkout page) and used a WP 3.3 custom menu. I then inserted the compact cart on the "Header" custom menu and applied custom styles to achieve the "effect" I was looking for. This enables customers who leave the checkout page to click a link in the header that returns them to the checkout page.
It isn't perfect since I had to modify some core files from the shortcode extender plugin (which I assume will need re-modified upon plugin updates), but I got it just the way I wanted nonetheless. Thanks!