Question on RC4 algorithm

I started reading RC4 from a book and was not able to understand some phrases correctly.

The RC4 algorithm is remarkably simple and easy to understand. A variable length key of from 1 to 256 bytes is used to initialize a 256-byte state vector S. At all times S contains a permutation of all 8-bit numbers from 0 to 255.

From the above my interpretation is that if suppose we use Java as our programming language

1. Each character is 2 bytes and the key length can be from 1 till 128(256/2)length long.


2. A vector/extendable-array is created array is created. But what is the length of the array? Is the size of array is 256?


3. At all times array S contains a permutation of all the 8-but numbers from 0 to 255? Could someone explain this to me.

Kindly help me as I am feeling lost in my first chapter to study cryptography.

Regards, Pradeep