Header image size and text

Hi, I just bought the Responsive Pro template and have a couple issues you maybe can help me solve: 1 - In the template preview the header image is nice and big, while once I upload my image and crop it to the size requested, it shows up much smaller (full width but but shorter in height). 2 - How do I change the color and/or font of the text that appears on the header image and of all other text (heading, paragraph, so on...). With CSS? 2 - I would like to have the big header image on all pages, but different on every page and with a different text on it. I tried using the Featured Images but then I can't find how to add the text on them. Thank you very much for your help!