Last week, we posted a look at the iPhone 4 cases Apple is offering for free to users—one case per iPhone, unless you bought one or more Bumper cases from Apple before the giveaway began. Today, we updated our iPhone 4 Case Program - Best + Worst Picks article to provide additional photographs and details on some of the case picks, and we also wanted to answer a few e-mailed reader questions here. “Which in your opinion is the most visually…