i would strongly recommend dudb. it includes almost everything you would need. it even hashes the passwords.
http://dracoblue.net/download/dudb-24/31/
natives:
native udb_Exists(nickname[]);
native udb_Remove(nickname[]);
native udb_UserSetInt(nickname[],key[],value);
native udb_UserSetFloat(nickname[],key[],Float:value);
native udb_UserSet(nickname[],key[],value[]);
native udb_User(nickname[],key[]);
native udb_UserFloat(nickname[],key[]);
native udb_UserInt(nickname[],key[]);
native udb_CheckLogin(nickname[],pwd[]);
native udb_Create(nickname[],pwd[]);
native udb_hash(buf[]);
native udb_encode(nickname[]);
native udb_decode(nickname[]);
as for the command prosseser, i prefer dcmd, but you might want to try zcmd because dcmd is a bit more code to script