Yes. Editing an existing image (no matter how much/little) does not void the original creators copyright and without permission is still considered infringement.
Altering a copyrighted painting to teach a technique is still copyright infringement as that falls under derivative works.
No. If an image is trademarked for anything, you need specific permission from the owner of the image in order to use it. No matter what you use the image for, the owner of the image can still sue you for copyright infringement (I've seen it happen).
Any owner of a copyright can sue for infringement as long as the copyright is still valid (i.e., for 95 years from publication).
The image is still owned by and under copyright by the original creator of the photographer who created the ORIGINAL image. Taking a photo of someone else's photo does not transfer the copyright to you (the iPhone owner).
No, because nothing is being stolen. Rightsholders typically feel it is a form of copyright infringement, though, which is still illegal.
A reprographic image would be infringing on the original.
No. Copyright infringement is a civil matter, so you won't be 'arrested' for illegally downloading (streaming is still downloading in a way) a movie, but you can be sued.
Copyright on Satie's Gymnopedies has expired, but recordings are almost certainly still protected, and new significantly edited and/or annotated editions may have been separately registered.
If you are using a Copyright Video and/or Audio, you need expressed written permission from the artist(s) before you can publish it. If you do not get this permission, and still publish it, you risk being sued for Copyright Infringement.
It depends on whether the work is still copyrighted, whether you have permission, and whether your particular use is exempt from copyright infringement. Copyright symbols have been completely optional as a requirement for copyright ownership for over 20 years, under US copyright law. You have the burden of making sure that the work is not copyrighted before you use it without obtaining a license, if one is necessary for your use.
The names are in the public domain, as the original work is from 1900. However, images from the 1939 film are still protected.
Not always. Plagiarism is making a false claim that you created something original. If you copied a public domain source, it is not a copyright infringement, but still plagiarism. For example, you download a NASA photograph (all works created by the US government are public domain in the USA), modify it and submit it to a photo contest as your original work. That is plagiarism, not copyright infringement.