I'm not in Missouri, but a friend of mine is a foster parent. They just want a clean home and the children need their own rooms, or (I think) can share a room with one other same-sex child, depending on the age. They also had to attend foster meetings/classes every month, and cooperate with whatever setup the system had put in place for the children seeing their biological family. The biggest point they emphasized is you're not "saving kids from their horrible parents," you're providing support for the children and their families, because there are lots of different situations that require the foster system. So being a positive role model and a positive support for the children is the most important part.
Missouri Foster care program focuses on the evaluation of the child's needs and providing activities that helps the foster parents and the children to adjust to the changes. Age and gender are considered and positive role model is emphasized to the foster parents. Find out more from http://www.dss.mo.gov/cd/fostercare/fcac.htm.