1 No - your current sentence is ungrammatical. You probably should use *because* instead of *cause*

> The main reason I need an extension is **because** the literature survey took so long.

If you want to keep the word cause, you can use the slightly more stilted

> The lengthy literature survey **caused** me to need an extension.

2 Use of the word **cause** is given in the dictionary:

> **Cause** *Noun*
>
> A person or thing that gives rise to an action, phenomenon, or condition.
>
> *Verb*
>
> Make (something) happen: "this disease can cause blindness".