Questions on Adonis Theme free

Hello, I am using free Adonis wordpress theme for my website : http://theoderenne.fr/ I am using Gmedia and Nextgen pluggins for my photo galleries. I have a few questions regarding the Theme : 1. Apart from the main Menu + Homepage, I find the margin on the sides (left + right) too big, and I would like to make it more "full screen". Where can I modify these parameters ? Is there a way to make it in percentage of the size of the screen ? 2. When I am in Homepage, I can see a picture in full screen : that is great. But when I am in other pages (Portfolio, Blog..etc), I would like to keep the Menu quite thin, but still with a picture ! Now the image needs to be the same between Homepage and the rest of the Menu (I cannot have different pictures it seems), and I find it too thick. Thanks in advance for your help, Best regards, Theo