Hi Jomathan,

Ad 1. Yes, it does know.

BaseDataBoundControl:
protected internal override void OnPreRender(EventArgs e)
{
   this._preRendered = true;
   this.EnsureDataBound();
   base.OnPreRender(e);
}

protected virtual void EnsureDataBound()
{
   try
   {
       this._throwOnDataPropertyChange = true;
       if (this.RequiresDataBinding && ((this.DataSourceID.Length > 0) ||
this._requiresBindToNull))
       {
           this.DataBind();
           this._requiresBindToNull = false;
       }
   }
   finally
   {
       this._throwOnDataPropertyChange = false;
   }
}

protected virtual void OnDataPropertyChanged()
{
   if (this._throwOnDataPropertyChange)
   {
       throw new
HttpException(SR.GetString("DataBoundControl_InvalidDataPropertyChange", new
object[] { this.ID }));
   }
   if (this._inited)
   {
       this.RequiresDataBinding = true;
   }
}

As you can see data is bound only once (for the same datasource parameters).

Ad 2.

You can always set SelectedValue in the Page_load, even before the data has
been bound, as the SelectedValue is stored in the temporary variable until
the next databinding:

ListControl (base class for lis type control, i.e. dropdownlist, bulletedlist)
public virtual string SelectedValue
{
   get
   {
       int selectedIndex = this.SelectedIndex;
       if (selectedIndex >= 0)
       {
           return this.Items[selectedIndex].Value;
       }
       return string.Empty;
   }
   set
   {
       if (this.Items.Count != 0)
       {
           if ((value == null) || (base.DesignMode && (value.Length == 0)))
           {
               this.ClearSelection();
               return;
           }
           ListItem item = this.Items.FindByValue(value);
           if ((((this.Page != null) && this.Page.IsPostBack) &&
this._stateLoaded) && (item == null))
           {
               throw new ArgumentOutOfRangeException("value",
SR.GetString("ListControl_SelectionOutOfRange", new object[] { this.ID,
"SelectedValue" }));
           }
           if (item != null)
           {
               this.ClearSelection();
               item.Selected = true;
           }
       }
       this.cachedSelectedValue = value;
   }
}

HTH