Developers

I would like to add a TOC (table of contents) to each post on my blog. What is the best way to accomplish this?

The title says it all. I'm currently using Commento as an external service.

Would it be possible to show all entries excluding posts with a specific tag?

Is there a way to change or manipulate stylesheets for minor changes that can affect the entire site? For example, just want to change the behavior of hyperlinks without manually recreating the existing pages.

I would like an image used in my blog post to appear when I share the post on Twitter, or Facebook.