Can the Guild Store popup get the buttons 'Store Items', 'Report', 'Add Tags', and 'Remove Tags' somewhere on it..
Could just get rid of those links from the bottom of the Guild Manage page and have the Guild Store managed from the pop up
Also, when you go to 'Add Tags' could the page automatically be on the 'Show All' item type instead of Helmets? Could there also be a select all button where it ticks everything available under the item type you are looking at..
or the tagging process could be changed to how the auction house listing and decomposing pages work can select each one or hit the Invert Selection button which will be next to the Add/Remove Tag(s) button..