Thanks for your updates with the additional information and questions.
You wrote “batch tag/categorise my media” – you can find more information on batch tagging in the topic I referenced above (Why are there two Categories sections?) and the topics it links to.
You wrote “Create a paginating Gallery/Portfolio of images based on my category structure” – thank you for starting a new topic for this question (Gallery Hierarchy – Parent>Child>Grandchild). I will respond to this question in that topic.
You wrote “Display Title/Caption” – here is a recent topic along similar lines: Media upload date. Generally, you can add parameters to your [mla_gallery]
shortcode to display a custom Caption value, or you can set up custom markup and style templates to compose any kind of gallery display you want.
You wrote “The image itself links to fullsize/lightbox etc.” – MLA provides a reasonable gallery display with many options for enhancing it, such as custom templates. However, there are many excellent gallery/slideshow/lightbox plugins that provide more features. MLA can work with many of them; here is a recent topic with examples: Good SlideShow add-on.
You wrote “I guess all styling is done by CSS?” – The short answer is “yes”. Most themes provide CSS styles for the WordPress [gallery]
template and MLA’s [mla_gallery]
template provides class attributes and markup as close to the WordPress values as possible. Again, custom style and markup templates can be used to give you complete control of your gallery displays.
You asked “What is an attached file vs an unattached file?” Early versions of WordPress used the idea of “attaching” images to a specific post/page (the “parent”) so the [gallery]
shortcode could easily compose a gallery of the items “attached” to the post/page. This has become less useful over the years and starting with WP 3.5 galleries were composed by selecting one or more images in the “Create Gallery” popup window and passing the list in a shortcode parameter, ids
. Plugins like MLA add taxonomy support to Media Library items and this is far more flexible. So, an “attached” item has a post/page ID value in the “parent” field and an “unattached” item has a zero in that field.