post option, foreach, session arrays problem

[nitediver]

This is a simple shopping cart, i've few problems,

1.How to post selected value from drop down list in 2.php?

<?php
echo $qprod['name'];

echo "<select name=\"size\">";
while($row = mysql_fetch_array($qsize)){
echo "<option value=\"$row[size_id]\">$row[size_number]</option>";
}
echo "</select>";
?>

2.How to set parameter for foreach in 3.php, since Im sending two variable($id & $size)?

foreach($_SESSION['cart'] as $id => $q){

0.php

<?php
include "../function.php";
connect();
session_start();

$qprod = mysql_query("SELECT * FROM kart ORDER BY id ASC");
?>
<table>
</tr>
<? while($rprod = mysql_fetch_array($qprod)): ?>
<tr>
<td>
<? echo $rprod['id']; ?>
</td>
<td>
<? echo $rprod['name']; ?>
</td>
<td>
$<? echo $rprod['price']; ?>
</td>
<td>
<a href="1.php?id=<?= $rprod['id'] ?>">Buy</a>
</td>
</tr>
<? endwhile; ?>
</table>

1.php

<?php
include "../function.php";
connect();
session_start();

$id = $_GET['id'];
$qsize = mysql_query("SELECT * FROM a_size ORDER BY size_id ASC");

?>

<form name="prod_select" method="post" action="2.php?id=<?php echo $id ?>&action=add">
[code=php]

<?php
echo $qprod['name'];

echo "<select name=\"size\">";
while($row = mysql_fetch_array($qsize)){
echo "<option value=\"$row[size_id]\">$row[size_number]</option>";
}
echo "</select>";
?>

<input type="submit" name="add" value="Add">
</form>
[/code]

2.php

<?php
include "../function.php";
connect();
session_start();

$size_id = $_SESSION['size_id'] = htmlentities($_POST['size_id'], ENT_QUOTES);

$id = $_GET['id'];
$size_id = $_GET['size_id'];
$action = $_GET['action'];

switch($action){
	case "add":
	$_SESSION['cart'][$id]++;
	$_SESSION['cart'][$size_id]++;
	break;
	case "remove":
	$_SESSION['cart'][$id]--;
	$_SESSION['cart'][$size_id]--;
	break;
	case "empty":
	break;
}
header("location:3.php");
?>

3.php

<?php
include "../function.php";
connect();
session_start();

$id = $_GET['id'];
$size_id = $_GET['size_id'];

if(!$_SESSION['cart'])
{
	echo "Cart Empty!";
}else{
foreach($_SESSION['cart'] as $id => $q){
	$query = mysql_query("SELECT name,price,size_number FROM kart,a_size WHERE id='$id' AND size_id='$size_id'");
		list($name, $price, $size) = mysql_fetch_row($query);
		$subtotal = $price * $q;
		$total += $subtotal;
		echo $name." - ".$size." - ".$q." - $".$subtotal."<br>";
	}
}
?>

Result:
[text]- - 20 - $0
- - 23 - $0
- - 3 - $0
[/text]

Thank you, any advice will be appreciate.