Insert for each symbol (upside down A) in an emacs text document

[Angus Comber]

I am writing up some mathematical documents and would like to use the for
all (upside down A) and there exists symbol (backwards E).

Firstly, how do I insert these symbols?

Secondly, can I insert into a text document?  Or does it have to be a
unicode document?

Thirdly, will the symbols be visible in the document when viewing on -
screen??