I am making a program from 1st person point of view. I would like the camera to be moved using the mouse, preferably using simple code, like from XNA

var center = this.Window.ClientBounds;
 MouseState newState = Mouse.GetState();


  if (Keyboard.GetState().IsKeyUp(Keys.Escape))
  {
      Mouse.SetPosition((int)center.X, (int)center.Y);
      camera.Rotation -= (newState.X - center.X) * 0.005f;
      camera.UpDown += (newState.Y - center.Y) * 0.005f;
  }

Is there any code that lets me do this in Unity, since Unity does not support XNA, I need a new library to use, and a new way to collect this input.

this is also a little tougher, since I want one object to go up and down based on if you move it the mouse up and down, and another object to be the one turning left and right.

I am also very concerned about clamping the mouse to the center of the screen, since you will be selecting items, and it is easiest to have a simple cross-hairs in the center of the screen for this purpose.

Here is the code I am using to move right now:

using UnityEngine;
using System.Collections;

[AddComponentMenu("Camera-Control/Mouse Look")]

public class MouseLook : MonoBehaviour {

public enum RotationAxes { MouseXAndY = 0, MouseX = 1, MouseY = 2 }
public RotationAxes axes = RotationAxes.MouseXAndY;
public float sensitivityX = 15F;
public float sensitivityY = 15F;

public float minimumX = -360F;
public float maximumX = 360F;

public float minimumY = -60F;
public float maximumY = 60F;

float rotationY = 0F;

void Update ()
{
    if (axes == RotationAxes.MouseXAndY)
    {
        float rotationX = transform.localEulerAngles.y + Input.GetAxis("Mouse X") * sensitivityX;

        rotationY += Input.GetAxis("Mouse Y") * sensitivityY;
        rotationY = Mathf.Clamp (rotationY, minimumY, maximumY);

        transform.localEulerAngles = new Vector3(-rotationY, rotationX, 0);
    }
    else if (axes == RotationAxes.MouseX)
    {
        transform.Rotate(0, Input.GetAxis("Mouse X") * sensitivityX, 0);
    }
    else
    {
        rotationY += Input.GetAxis("Mouse Y") * sensitivityY;
        rotationY = Mathf.Clamp (rotationY, minimumY, maximumY);

        transform.localEulerAngles = new Vector3(-rotationY, transform.localEulerAngles.y, 0);
    }
    while (Input.GetKeyDown(KeyCode.Space) == true)
    {
        Screen.lockCursor = true;
    }
}

void Start ()
{
    // Make the rigid body not change rotation
    if (GetComponent<Rigidbody>())
        GetComponent<Rigidbody>().freezeRotation = true;
}
}

This code does everything except lock the mouse to the center of the screen. Screen.lockCursor = true; does not work though, since then the camera no longer moves, and the cursor does not allow you to click anything else either.