BTW, that movie is pretty good.
You may not know what exact you want/like, and/or that might change over time. You have the luxury to think about it, you have the option/willingness/power to pursuit... You are already in great shape and living a wonderful life.
Children, whether that's investment or responsibility. Responsibility is for sure. Investment or not, depending on whether you consolidate into one book, or keep them seperate but only looking at your own book.