enable jquery ui effects in theme .info file
No, it's not possible to add a Drupal library through a module or theme's .info file. You can add single CSS/JS files, but not a defined library.

That means it's physically possible to download separate copies of system libraries and include them statically in your theme, but you should not do this. It's not the 'Drupal' way, and it makes things very difficult to maintain.

You're right in thinking the logic shouldn't be in your page.tpl.php file, it should rather be inside your theme's hook_preprocess_page function in the template.php file.

That way the library will be added in time to be included in the page, you maintain a nice level of separation between logic and display, and your theme will be protected in the case that core updates need to be applied to the libraries you're using.