Illustrations of professions / for children

I need 27 illustrations of professions (farmer, nurse, teacher, postman, butcher ...). For each profession, I need a drawing of a man and one of a woman.
So we need 54 nice and modern illustrations.
The illustrations must be done with Adobe illustrator and I need to have a ".ai" file.
I need to know how long on average each illustration takes you, and long you think the whole project would take you.
If I am satisfied with your work, I have many other illustration projects for the near future.
I attached a file to give you an idea of the type of design I am looking for.
I will ask for a example of woman and man before the invoice (pictures in jpg 72dpi, just to see if the design is good for my project.