Help! How to change promotion headline's text color, and other issues- Fullframe

Hi everyone! :) I'm currently using the Fullframe theme, free version. I need your guys help because I haven't published my website yet due to the issues below. I tried everything, looked for an answer in foruns and even tried lots of codes suggested but couldn't manage to solve the problems. It's been days I'm trying, so I'd be very grateful if someone told me how to fix it. Please be very specific because I'm not acquainted with html codes etc. 1- I managed to change the promotion's headline font and size of the title AND text. It's not possible to change both separately. But although I changed the title's color white, for some reason the same didn't happen to the text: the title went white but the text still remains with the default color, a light gray that makes it hard to read over the silver background I set. 2- How can I remove the line at the bottom of my post, displayed on my frontpage? 3- How can I change the frontpage's featured content's thumbnails size, add a border etc? 4- Last but not least: how the heck do I center my galleries? This one is driving me crazy. Thank you in advance! Laura