All I want is/are a book and a pen.

[thehammer]

Which ones are correct?

1- All I want is/are a book and a pen.
2- A book and a pen are/is all I want.
3- The only thing(s) I need is/are food and a shelter.
4- Food and a shelter is/are the only thing(s) I need.

 

[Barque]

1- All I want is/are a book and a pen.

"Is" comes more naturally to me though "are" is probably the technically correct answer. I suspect it's the same with many people.

2- A book and a pen are/is all I want.

Are.

3- The only thing(s) I need is/are food and a shelter.

You need "things" here because you're referring to more than one thing and you'd need to use "are". "Shelter" in this context is used uncountably and doesn't need an article (though in some contexts it cam be countable).

4- Food and a shelter is/are the only thing(s) I need.

You'd need to use "are" and "things".

Also, like the first sentence, I think many people would say "All I want is food and shelter" rather than "All I want are food and shelter".