All these questions still floating around -- why not just ask her straightforwardly? Are you looking for someone to share your life with *along* with your husband or *instead* of your husband? Are you and your husband looking for a triad? Much more efficient than speculating here.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.