B.O.
If she is telling you when she has a BM, that is a major step in potty training. Get her a seat, but don;t push it too hard. Explain to her what the seat is for, and that she can use it when she wants. Give her time to explore the seat at her own pace.
She likes taking her clothes off because it is a new skill:) It is a wonderful sign of how well her fine motor skills are developing:)