fixed amount on simple donations?

Is it possible to set a fixed amount on each donation with "simple donations" activated?
Also, is it possible to NOT display the number of donators and the amount?
This is ment to be a site for a christian womans organisation
Url: http://kvinneverk.kunde.reklamebanken.com/archives/bli-fast-giver/bli-fast-giver (password: vekkelse)