Hello dear User and Administrators of Omeka,
I have a serious task in front of me. I need to display all Items as a Grid with some descriptions under them. Also, because i will have thousands of items, i need to be able to add a feature to sort items. Like amazon has: http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Dphoto&field-keywords=camera (on the left side of the page). Any help will be very appreciated, thank you.
There are no quick answers to your question. For the first, you would need to create custom css and possibly edit your-theme/items/browse.php to create a grid for the browse items page. You could use the CSS from Exhibit Builder's Gallery layout as a guide.
https://github.com/omeka/plugin-ExhibitBuilder/blob/master/views/shared/exhibit_layouts/gallery/layout.css
If by "sorting," you're referring to the facets (Department, Price, and so on), you would need to either use the SolrSearch plug-in.
For regular sorting, you can allow the user to sort by any metadata element by adding it to $sortLinks in your-theme/browse.php. By default this includes Title, Creator, and Date Added. You can also link to a pre-sorted page by appending sort_field=Element+Set%2CElement to the browse URL