Where in .edmx-file I can find the assembly name? Second, when I create my own partial class, how do I make it to appear in the same assembly?
There is no assembly name in the edmx file. The code generated from the edmx file becomes part of the project the edmx file is part of and therefore become part of assembly that is compiled for this project. Partial classes are mostly a compiler trick and when you compile partial classes the compiler will combine all the partial classes into one and in the assembly you will always have just one class.