If you catch up with the Imam after he has stood up from Ruku`, this means that you have missed the Jumu`ah prayer. But if a person does not catch up with the prayer for a reason that is beyond his control, then there is no sin on him.

What is meant by ‘stepping over the people’s necks’ is that the one who does that lifts his foot above the shoulders of those who are sitting in order to pass them. Prophet Muhammad forbade stepping over people’s necks during the Friday Khutbah because that causes annoyance to those who are sitting. An exception to the prohibition on stepping over people’s necks is made for the Imam if he has no way to reach the Minbar or Mihrab except by stepping over people’s necks.

If a woman prays Dhuhr in her house on Friday, then she should pray the Sunnah prayers that come before and after Dhuhr, as she does daily.