Is the travel period considered an 'iddah for a divorced woman, as well as an 'iddah for zina (illicit sexual relations), so that she may be married after repenting from zina and agreeing to a lawful marriage?

What you have done are grave abominations, among them adultery, whose sin is magnified by your being married and committing this indecency with a married woman or a woman in her 'iddah (waiting period). You may also have been the cause of corrupting her relationship with her husband. A severe warning has been mentioned in the Sunnah for anyone who incites a woman against her husband. You must perform sincere repentance for all that has been mentioned. If the woman repents sincerely and her 'iddah has ended and she has been cleared, then there is no harm in you marrying her.