Comment 1 for bug 170514

You can already do that by converting the image to a
pattern-fill rectangle (Edit > Objects to pattern), then
switching to Node tool (F2) and dragging the top left and
bottom right handles of the rectangle. The bitmap will be
cropped. If you want more complex crop shapes, convert the
rectangle to path (Ctrl+Shift+C) and use the Node tool to
move/add/delete nodes.

A better solution will be available when we implement crop
and mask tools. They are being worked on.

We don't have tabs but you can still open any number of
documents at once. As for exporting, you can do batch export
using Inkscape's command line options by writing a simple
script. See `man inkscape' for options.