How to handle/manipulate (hierachical) VO's and remote proxies

Hi,
I've some general questions regarding handling VO's and remote proxies:

1)
VO's are used for server side communication and the VO's represents the data model, right ?
I've often read that VO's should contain only properties, no methods. Is it still a good way to implement also some methods to manipulate the VO itself at client side ?

2)
Is it the right way to pass a reference of an VO to the proxy data element ?

3)
Should the proxy implements some methods to manipulate the passed VO or should we use the
methods inside the VO to do this (see question 1) ... or should we use an additional "model class" ?

4)
What could we do, if we'd like to make the application able to work offline ?
Is one way to implement an additional "offline proxy" and switch between offline and online modus (proxy) ?

Hmm... seems that I'm not really able to formulate my questions in an understanding way...
perhaps you can provide some well desigend sample code for the example below ?

Many thanks in advance !
Olaf

Example:
Imagine we've a basket (BasketVO) that's able to pick up some items (ItemVO).
Inside the BasketVO we have a method "addItem()" to add an new item to the basket.
We'd like to save a new item to the remote server's database directly after e.g. clicking an "add item" button by using the "AddItemCommand".
(Following code is only an example to clarify my questions)


// BasketVO
public class BasketVO
{
	public var userId:String;
	public var items:ArrayCollection;

	public function BasketVO (userId:String):void
	{
              this.userId = userId;
	}
 
        // adds new item to the basket
        public function addItem(item:ItemVO):void
        {
                this.items.addItem(item);
        }

}

// ItemVO
public class ItemVO
{
	public var itemNo:int;
	public var price:Number;
        public var count:int;

	public function ItemVO ():void
	{
	}

        // is it a good idea to place this kind of method here ?
        public function calcSum():Number
        {
                return count*price;
        }
}

// the proxy 
public class BasketProxy extends Proxy implements IProxy
{
       public static const NAME:String = 'BasketProxy';
     
       private var _basketService:RemoteObject;
       
       public function BasketProxy(userId:String)
       {
            super( NAME, new BasketVO(userId) );

            // set remote service
            _basketService = new RemoteObject();
            // ...

            _basketService.addItem.addEventListener(ResultEvent.RESULT, onAddItem);

       }

       public function get basketVO():BasketVO
       {
             return data as BasketVO;
       }

       // calls remote service to add a new item 
       public function addItem(itemVO:ItemVO):void
       {
           // add item to remote basket and save item into DB
            _basketService.addItem(itemVO);
       }

       public function onAddItem(event:ResultEvent):
       {
           var returnedItem:ItemVO = event.result as ItemVO;
 
           // add item to local basket
           // is this the right way ???
           basketVO.addItem(returnedItem);

          // send notification
          // ...           
       }
}	

// command that's add a new item
public class AddItemCommand extends SimpleCommand
{
	override public function execute(note: INotification ) :void	
	{
            var itemVO:ItemVO = note.getBody() as ItemVO;

            var basketProxy:BasketProxy = facade.retrieveProxy("BasketProxy") as BasketProxy;;

            basketProxy.addItem(itemVO);
	}
}