the crystals, soft sponge, water with WUL, polish off with an old vest. You may find you can unstring them from the metalwork. If they have a tobacco smoke film <boak> use meths then repeat the WUL and vest.
to treat the rust, use Jenolite rust remover from a motor accessory store. No other rust treatment, must be Jenolite liquid which is an acid. Apply with a small paintbrush, just on the rust. Gloves, goggles, follow instructions etc. The brass plating will be gone though. Keep a bowl of water handy to wash off any drips or splashes immediately.