I frequently receive requests for help with assignments regarding Willa Cather's life and work.

Here are the general recommendations I can make; beyond this, you need to complete the work on your own, and I can't help you any further.

The best and most important thing you can do is read and re-read the work very carefully. Take notes as you read along -- what is surprising? what do you enjoy the most? what is confusing? Often these points of interest provide beginnings of good thoughts for essays. Your teacher expects you to explore the work on your own, and there is no better way to do this than to read and re-read Cather slowly and appreciatively.
Students often ask for specific information or articles on the Web. All that I know of is collected here on this site, but there is very little available. Your best resource is still your library, whether at your school or in your community. Even if your library does not have the materials you are seeking, they are often able to order them on loan from other libraries. Librarians are very helpful about this.
The standard Cather bibliography is entitled "Willa Cather: A Literary Life" by James Woodress (1987). John J. Murphy has edited a collection of "Critical Essays on Willa Cather" (1984).
The journal which focuses exclusively on Willa Cather's life and work is called The Willa Cather Pioneer Memorial Journal. A local library may subscribe to this. The journal is indexed by a publication entitled The MLA Bibliography. Some libraries have access to this index online. Here you can search for keywords in published articles, including the WCPMJ.