help problems about vsftp

Dear All
I am a novice, recently successfully configged a vsftp server in the redhat linux 9. Now I want to add several new functions could you please tell me how to actualize them?

1. How to make special customs login vsFTP at appointed time, and other customs can visit my vsFTP server any time?
2. How to make different document different privilege? My linux has 5 users, each user has his own 2 document, one is read only, the other can be write and read.
3. Is there any latent danger? If somebody knows other's user name, they try password take pains, one day thay can get true password. which log can I see that somebody has tried password time to time ??

thank you for helping me!

1. I'm not sure exactly what you mean. Are they supposed to only be able to log in at a certain time of day?
2. How about using the permissions system that is built-in to Linux itself? Try "info chmod" for info.
3. That would be vsftpd.log, if I recall correctly.