Customize wordpress theme and make plugin that adds image to post after 15 comments and a different image after 30 comments

I need the following customized on my wordpress theme In Homepage 1. Change layout of posts featured images in homepage to 3 in a row boxes. Currently the layout has one post featured image per row with summary content next to it. Remove the post description, date and author, leaving just the title and featured image. 2. side menu remove white boxes and make menu show up as a simple list. simple edit to css. In Post 3. Add space next to post featured image so I can add adsence code or image. 4. Make comments show in squares 3 in a row with minimum size, keep only commenters name, and make it so I can edit css. 5. Make plugin in which after FIRST 15 comments a box will show with images or javascript code, and after 30 comments a different box with image will show with different image or javascript code. I need to be able to edit and insert image or javascript code for these boxes somewhere on the dashboard. Keep all new css at the bottom of the css page where I can easily find it.