Plugin compatability and thumbnail layout

Hi

I'm pretty close to handing over some money for your tool on the whole it looks great and for someone like myself who knows what they want but not how to get there, I think this would be a great tool.
A couple of questions though. Can I add CSS styling to plugins? I want to use a slider plugin and I also use contact form 7 on a couple of websites both of which I want to add my own CSS to.

Also I want to design up something similar to the gallery theme is this type of layout possible with themeframe? Heres a link to what I mean. http://upthemes.com/demo/?theme=gallery

Thanks D