Adding Custom Configuration Options for Blocks

Hi everyone, I'm pretty new to Drupal and I have been baffled by the whole system. It's powerful yet confusing at times. Anyway, I don't really know if my question falls under the "modules" or the "theme" section so I'll post here anyway.

Is it possible to add a hook somewhere to add custom options on a theme basis for block display? Currently, I realize that it is possible to allow for module-based custom settings but I don't see an option to allow for theme-based options. I would like to add an option to allow the user to choose between two different block styles to display and also some colour schemes for the different block styles as well. I've tried looking at the API documentation for some hooks but couldn't exactly find any.

Also, after I have managed to add in this option into the "customise block" form, how do I store the data and retrieve the data for the template to style it?

Thanks in advance.