Passing by the Miqat without entering Ihram then returning to it again to enter Ihram

Q: I intended to perform `Umrah (lesser pilgrimage) from my residence in Al-Bahah, and I took the bus heading to Makkah. We were about twenty people heading to Makkah with the intention of performing `Umrah, and the rest of the passengers were also about twenty people heading to Jeddah in the same bus. When we arrived at the Masjid located in the Miqat (site for entering the ritual state for Hajj or `Umrah), we asked the driver to stop at the Miqat for making Ihram (ritual state for Hajj or `Umrah), but he continued driving without stopping at the Miqat. Some passengers supported him in his act claiming that they have their families with them and they are heading to Jeddah. We protested and complained that we wanted to perform Ihram and we know that we are not allowed to pass by the Miqat without entering Ihram thereat. However, the driver, who was a Pakistani, said: "I have no knowledge about it". Some passengers encouraged him to carry on his journey. We asked the driver to stop at the police station, and this was to place a complaint against him, but he continued driving in the direction of Makkah. It was morning and we passed the Miqat by a long distance. He went on driving until he reached Makkah and took us to Al-Haram (The Sacred mosque in Makkah) where he announced: This is the stop for those who will get off in Makkah and after that the coach will head directly to Jeddah. We called the police and we all, (Part No. 10; Page No. 113) the twenty people heading for `Umrah, got off the bus. While we were discussing the issue with the police, who was also busy in organizing the traffic beside Al-Haram, the driver drove off with the other passengers heading to Jeddah and he got quickly far away from us. Thirteen people among us gathered together and hired a bus and went back to the Miqat located at Muharram Valley. We all entered Ihram and came back to Makkah to perform `Umrah. Is what we did right? Is our `Umrah complete in this case, or do we have to do anything?Another question is regarding a colleague who performed Hajj (pilgrimage) last year and a female pilgrim authorized him to slaughter Hady (sacrificial animal offered by pilgrims) on her behalf, giving him a sum of money for this purpose. However, due to the constraint of his time during Hajj season, he left Makkah and went back to his work without slaughtering the Hady. Some friends advised him that he should slaughter the Hady during his Hajj this year; that he would discharge himself from this duty at the very time and place of Hajj. My question is: Does he have to do that, or can he slaughter the Hady in the nearest possible time and place in order to fulfill the obligation entrusted to him by this female pilgrim? Please provide us with a correct opinion regarding this issue, may Allah benefit you.