Is it permissible to postpone the intention for Hajj until reaching Jeddah and performing the Ihram from there, in the event that one arrives in Jeddah for the purpose of escorting pilgrims to Egypt? And is it necessary to return to Rabigh to perform the Ihram from there, or is it sufficient to perform the Ihram from a hotel in Jeddah?

If your purpose in traveling is to perform Hajj or Umrah, it is not permissible for you to pass the Miqat without entering into ihram. If you do pass it, you must return to it and enter into ihram from there, and nothing further is required of you. However, if you do not return to the Miqat, then you must sacrifice a sheep in the Haram and distribute it among the poor.