You can use a song that is entirely your own work (the song itself, and the recording of it), or one that is entirely in the public domain. There are a few circumstances in which your use would be considered "fair," meaning there could be an exemption in the law, but nearly all uses of others' works (either the song itself, or the sound recording, or both) require permission.
You need a synchronization license for the song itself, and a master use license for the recording you want to use. The song is administered by EMI (links below).
No, it is not ethical to use photographs without permission.
If varies from song to song. You would need a synchronization license (from the publisher) for the underlying song, and a master use license (from the record label) for the particular recording.
I think from your grammar and spelling you have bigger problems in regards to schooling then youtubes legality. The answer is yes if she is the legal copyright owner of the video. In other words you can't use an illegal video from youtube (or another youtube users work..without their permission).
No, it is not legal to use photos for advertising without permission from the copyright holder.
Assuming you're actually given permission to use a video camera on-board - Not without the prior written consent of every passenger - in case you capture their image !
Comment on the video or on their account
That actually depends upon what it is that you are using. If you use someone's car without permission, that is called stealing. If you use someone's movie without permission, that is called piracy. If you use someone's body without permission, that is called rape.
Images that are in the public domain are free for anyone to use without permission.
You have to get permission from the copyright owner.
If you want to record the song, most licenses are available through the Harry Fox Agency. If you want to arrange or reprint it, ask the publisher or print rights administrator, and to use it in a video project, you need a synchronization license from the rightsholder of the song, and a master use license from the rightsholder of the recording.For permission to publicly show a movie, contact the distributor.
With a license, yes. Without a license, no.