#4 would never be correct. Oracle specifically recommends against doing anything with online redo logs with respect to "restoring" them.

Media Failure and Recovery in Noarchivelog Mode

In this case, your only option is to restore a backup of your Oracle files. The files you need are all datafiles, and control files. You only need to restore the password file or parameter files if they are lost or are corrupted.

Media Failure and Recovery in Archivelog Mode

e) Recovery with missing online redo logs
Missing online redo logs means that somehow you have lost your redo logs before they had a chance to archived. This means that crash recovery cannot be performed, so media recovery is required instead. All datafiles will need to be restored and rolled forward until the last available archived log file is applied. This is thus an incomplete recovery, and as such, the recover database command is necessary (i.e. you cannot do a datafile or tablespace recovery).

As always, when an incomplete recovery is performed, you must open the database with resetlogs.
Note: the best way to avoid this kind of a loss, is to mirror your online log files.

Current documentation suggests that when doing a cold backup, you backup the control files, the .dbf files, and your parameter file (init.ora) and not the redo logs. If media failure occurs during the recovery method, a vaild closed database backup must exist in order to recover, otherwise an
incomplete recovery is done.