sqlplus / as sysdba
net localgroups ora_dba ... user1 user2 ... NT Authority\SYSTEM
Yes. It will require an uninstall, per the steps in the XE documentation, see http://docs.oracle.com/cd/E17781_01/install.112/e18803/toc.htm#CIHDDHJDa problem with the installation?
net localgroup administrators Administrators <domain>\<user1> <user2> ...
The utl_file is an older package, 11g uses directories to accomplish what used to require the utl_file utilities.PLS-00201 UTL_FILE must be declared.