It’s not on a first-come-first-serve basis, but rather it’s being considered on a rolling basis, i.e. applications are considered and awarded throughout the year. Theoretically anyway, since the Women’s Scholarship is currently closed until September.
They do not disclose the number of scholarships awarded.
What do you mean by ‘average period of scholarship window’? You usually have to register for an exam 12 months after being awarded a scholarship – more details will be included in your scholarship email.