There's a table with a list of files that need to be tagged before uploading. The table might get longer than the page height, so it's scrollable, and above it there are buttons that work on selected items:
As you can see, I tried to save horizontal and vertical space by omitting labels, and put the context on buttons themselves. Thus, Next file assumes the user has already read Select previous, and makes a connection that results in "Select next file". Similarly with moving selection and removing selected items.
Aside from Upload all (which uploads all, not just selection) and perhaps Remove, the blue buttons are rarely used. The order doesn't really matter much - except when the user really wants the files to be displayed next to each other - and selecting can be done via clicking the item on the table or a checkbox next to it (for multi-selection).
Is this layout acceptable, especially from accessibility point of view? Are there any guides or studies that touched upon this exact subject?