backup and recovery procedures / resetlog

I'm currently writing procedures for the backup and recovery of databases.

I read carefully the excellent paper of Howard J. Rogers but I've some questions.

1- Before doing a incomplete recovery, Howard strongly recommends a backup in order to be able to redo the recovery if necessary.

I don't understand why I could not redo the recovery.

I've a backup control file (trace) with each backup. If I want to redo the recovery, I should be able to use the backup control file and play again each archivelog until the resetlog. No ? If I do a backup of only the redolog files before the resetlog, I should have no loss. No ?

If I don't backup the Control Files before the resetlogs, what are the consequence for a incomplete recovery (except the need of using the backup controlfiles) ?

2- After a resetlog, Howard recommends to do a *cold* backup. A hot backup is not sufficient ? Why ?

Thank you very much in advance for you advices,

-- 
Bruno Jargot