Exist if profile exist and validating password

I'm working on a project that will allow user to reset his iseries password and re-enable his profile on their own. Having some difficulty with these two questions below and hoping someone can give me some pointers.

1) This project requires me to verify that the user profile entered on the screen exist on iseries. I'm thinking about using QSYRUSRI api to perform this verification. Would this api the best choice?

2) I'm planning to use CHGUSRPRF to perform the actual reset of the password and re-enable of the profile. I've noticed that CHGUSRPRF does not seems to perform that same password validation as the CHGPWD command does. CHGUSRPRF seems to accept any password. Is there an api that will allow me to make sure the password is acceptable before changing it thru CHGUSRPRF?

thanks