I have been wanting to write about Baba Yaga, she is a figure that interest me, but I want to know the history of her usage, where she came from, and how she is used in folklore. Also, if anybody knows any scholarly books/articles I could read that would be great too.
Baba Yaga is from Eastern Slavic, primarily Russian, folklore. Like most European folklore she dates from pre-Christian times, which means that there are no early written records.
Her role in folklore is the same as other witches in European folklore; and evil/grotesque old woman who lives out in the forest who serves as an antagonist figure. The big distinction here is that Baba Yaga is a named figure, which is rare among other witches. The classic Baba Yaga legends are ones that reinforce kindness and generosity, as well as not going into the deep forest.
The heroine escapes by befriending Baba Yaga's gate, dogs, and cat by being kind to them and giving them gifts. Another story has the same themes, except in this one the heroine must spin yard for the witch. She is routinely saved by mice, who spin the yarn for her after she gives them gruel.
So in short she is an old East Slavic figure, who is used as a reason to not go into the deep forest and to be nice and generous.
Source: Aleksandr Afanas'ev, trans. Norbert Guterman, Russian Fairy Tales, (Pantheon Books, 1975).
Follow-up question: where did the house on chicken legs come from?