Describe the differences between 'query_posts()' and 'WP_Query()'. If possible, describe where 'pre_get_posts' fits in. Describe some considerations you make when using images as part of your HTML/CSS buildout, including image format, size, and inclusion in HTML vs CSS. Describe some common security concerns related to using WordPress and strategies to harden an installation. How did you become interested in mobile and where have you used mobile development? How do you 'stay sharp' with industry trends and best practices?