Uploading images so that they are searchable How would I go about uploading images so that they are searchable, and so that the search results are actually displaying the image thumbnails?

How difficult would it be to integrate this search into the site search?
To include image data in the core search index, you perhaps could implement hook_search_info and hook_search_index to add the custom image field text attributes (alt, title text etc..) to the search index.

You can then theme the output of the search results by overriding search-result.tpl.php or using hook_preprocess_search_result to add the image thumbnail.

Further core Search API docs here