wpf and windows form

friends;
i using windows forms with visual stdio
i using drag and drop with windows form to add controls like button text box and so on

i find a new way to do that in wpf is column and row
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>

my question is:
1. why should i use this the code above?
2. what difference between drag and drop and this code?
3. what is benefit of using this code?
4. can i use drag and drop control in wpf and work like windows forms?