I'd start by clearing gout all the HEAD data in each of the pages you have, this will cause problems later on when you start from scratch.
Secondly, page templates and content inheritance are your friend. Take this example: I have a blog (/Blog) that uses a single page template. The template has a repeater on it that displays all the child blog posts in a list format using the Transformation/Alternating Transformation. In the Visibility section of the repeater, the "Show for page types" property is set for "cms.blog;cms.blogpost". This will allow this repeater to show when they are on a blog page type or a blog post page type.
On the same the same page template, I add another repeater that displays all the blog posts for a month since I want my users to "filter" posts by month and the standard hierarchy for a blog in Kentico is /Blog/Blog-Month/Blog-Post. So on this repeater I set the "Show for page types" property is set for "cms.blogmonth". Now when the user clicks on a month to view the posts, the list and detail will not show and I can setup a different transformation for the list if I'd like.
You can take this same approach with adding/removing items from the HEAD section. There is a webpart that is called HEAD HTML Code. In there add the code (< link > < script >, etc) and set the show for page types properties. Or even set a macro if you'd like on the visibility. There is no reason to create multiple templates for this type of thing.