To develop the female Kaito, focus on her relationships. She could have a mentor - like relationship with an older female thief who teaches her the ropes. In terms of her skills, she might be more attuned to using technology in her heists compared to the male Kaito. Also, explore her motives. Is it for the thrill, for justice, or something else? Her emotional journey as she becomes more and more like a great thief is also important to develop.
I don't think so. There haven't been any official announcements or indications that the HxH manga will continue. But you never know, maybe there'll be a surprise in the future.