Some speculations of mine:
• Salome is a part of the Kamisato Faction since she shares the same naming pattern as Ellen, Claire and Elza.
• Her powers might be related to her status as a little sister, and this may not change regardless of whether she is a Magician, an Esper, or a Gemstone.
• If she has the ability to manipulate based on the little sister concept, then the Level 5s do have some problems. Accelerator has Last Order, Kakine has Fremea, Mikoto has the clones, Mugino also has Fremea, Misaki has the Dolly clone, and Gunha has... pretty much everyone.
• There's also the possibility that Salome is designed after Esmeralda from Victor Hugo's Hunchback of Notre Dame. Her gypsy-like appearance, manipulative abilities, and a trinket hanging on her neck points to a similarity. Where's the goat, though?