As long as the painting is entirely original, no.
The site itself is entirely legal; the user-uploaded content, on the other hand, is very often infringing.
Without a license, yes.
If the painting is still protected, you would need a license.
Almost certainly, yes. The copyright laws protect the image of cartoon characters. When you sell it for profit you are stealing the right of the character's author to sell his own work.
There could be trademark issues, particularly if it can be proven that the intent of the user of the second URL is to cause confusion in the marketplace.
Ya, do it.
In the U.S.A., the Supreme Court has decided that recording a broadcast TV show is not copyright infringement.
Possibly but it entirely depends on your use of the copyrighted material, including whether or not it is for profit.
Several different types of thermometers (at the time called thermoscopes) were developed in the 16th century. As an invention, rather than a book or painting, etc, there would never have been copyright protection for such a device. In any case, the protection of copyright laws did not exist in the 16th century
A copyright lawyer it a layer who specializes in copyright laws and intellectual property laws. They handle cases concerning copyright infrsingement.
Plagarism or copyright Laws!
Drugs and other pharmaceuticals are protected under the patent laws not under the copyright laws.