Customize Worpress plugin - edit css and layout

I have another wordpress classified plugin or AWPCP installed on my site. The ads show up in vertical format with description to the right of the photo with about 10 ads/photos per page. I would like to have the option to display the ads in a grid layout eg 4 across and x amount down showing the photos on top and a snippet of the description below it. I'd also like the option to classify ads as; featured, newest, popular, random, best reviewed etc and have the featured ads display prominantly on the top of each page and highlighted or whatever....