I'll strongly advise you to let racle create her control file at thetime of DB creation.you certainy cant do without your data,redo and control files.

Your Second question...
try adding the Operating system user to the oradba user group( i'm assuming youre using windows).This should enable oracle authenticate you without you having to supply a username/password.you've logged in,you can try altering the password for sys and system accounts.

N/B to connect using OS authentication,simply type conn /@databasename as sysdba