Tumblr Theme Customization

Hello, I have a custom theme for tumblr that I would like to update. Right now you can view it here. [login to view URL] It only supports one size post and I would like to change it so that I can post different size posts within the current layout. The current size posts, double size posts and full width posts all while maintaining the same grid. While in tumblr I should be able to add a tag to an image with a size (small, medium, large) to determine the size of the post. I'd also like to get rid of the white frames around the text posts so that the text posts act the same as photo posts and reveal the title and read more link on hover over the image. Finally I'd also like the single post page (after you click the read more link) more on a post to be centered and be the same width as the full width posts. I can provide a pdf and current themes code to winning bidder.