You should have a very special reason to do that; for example you are developing for a micro-controller.
No.
No.
Because it cannot be understood by users. High level language like C can be understood by the user by looking at its source code. But assembly level language does not have any source code, its a language converted from high level language to low level language (assembly level language or machine level language) so that the language which the user could read/understand can also be read/understand by the machine.
Yes, it's actually about as low level as you can get. An example of a high level langauge would be Java
No.
No.
An assembler.
Why would you want to do that? The usual procedure is to translate a high-level language such as Pascal to machine language. If you really want assembly language - perhaps to see how the Pascal compiler does its work - then presumably you can use a disassembler to convert the machine language (the executable file) into assembly language.
Programs written in a high level language might be slower than ones written in Assembly language; but it is not always so, it is very easy to write un-effective programs in Assembly.
Assembly languages are low level languages, sometimes also called machine-level languages.
A High level language is a language like C, Pascal, Fortran. To convert, the easiest way is to use a compiler. A compiler will take the instructions written in a high level language and convert them into machine code which is the specific instruction set for that type of computer. Assembly language is just a human readable form of a machine code which is how the designers of the computer instruction set made it work. A disassembler will show the assembly language from machine code. But the compiler usually includes a lot of optimisations from a the high level language and will not often generate very simple assembly.
Assembly language is low-level because it has the least amount of abstraction between the source and the resultant machine code. That is, the translation from assembly language to machine code is 1:1. All high-level languages have much higher degrees of abstraction.