BigCommerce Shopping Cart Setup

Hello, This will be very simple for somebody who knows what they're doing. MUST have experience with BigCommerce platform and show examples. I'm looking for help doing the following: 1) Setting up a 2 for 1 promotion. I have 10 different DVD's I'm selling and I would like to setup a site-wide 'Buy 2 DVD's Get 1 Free' that automatically adjusts in the cart. These are for different DVD's (and NOT a volume discount of the same product). 2) Help creating an upsell after purchase. For example, somebody buys and a DVD and then are presented with an offer to purchase another dvd at 50% off. 3) Help create product links to integrate with my wordpress-based salesletters. So basically if somebody clicks on the 'buy now' button located on wordpress, the product is added to the BigCommerce shopping cart. That's it for now. Thank you.