Wordpress Template Modification & Widget Plugin

I have a WP template that needs some minor modification. I am happy with the current style of the template. On the Blog pages there needs to be 3 blocks added under the content (see mockup [login to view URL]). The content for these blocks will be added when the article is written and is specific to that article. I require this content to be as easy as possible to add and my preference for adding the content is via 3 text edit areas under the main edit area (see mockup [login to view URL]) I also need the article images to be display as per the Blog.pdf. There is 1 main image and up to 4 smaller images. The images will be need to be automatically resized and or cropped to fit the allocated spaces so as to look uniform. I wish the images to be added to the article through a widget in the "Add New Post" where the user can select which image is to be the main. I also wish the images to open in a modal window if clicked. I require this to be achieved with no core WP system modifications.