I imagine that this yarn would be great for embroidery. It is roughly the same weight as embroidery floss. Because silk is more fragile than most cotton and synthetics, I would recommend using base fabrics that have a a slightly more open weave structure and shorter pieces of yarn (to limit the friction of being pull through fabric continuously).
As for the borders, it should be beautiful for that! I would recommend hand washing the items you add a boarder too. Washing machines might tragically snag your hard work.
Hope this helps! Happy Crafting!