No, you don't need make redo volume snapshot when databse is in *BACKUP* state. Rado will be used in case of Oracle recovery only (when you have consistend database status and you put arch on that). You can use volume based snapshots (and mount .snapshot directory in case of recovery) or snapvault/snapmirror relaionship.
Sure enough. It came down to the way the DBA's have to start up the DB to recover it. They have to tell it to ignore the redo logs that are newer than the data files and start with new redo logs. In our old way of backing up DB's, this wasn't an issue since we snapped the redo log vol with all the others and restored it with all the others thus matching the timestamps. Even though there was no data in the redo logs that wasn't already in the DB.