How to create a global function/class ?

Question

Hi :)

I have a caple of questions:

1) How can i create a global function or a global class
that will be available to the entire project ?
2) I want to create derived class from the DataGridView class
and change it so it will fit to my needs, and after that i want
that this new dataGridView will be available in the ToolBox.
How can i do that ?
3) I want that the Minimize button of the ControlBox in a form
will do more things besides Minimizing the specific form, how
can i change what this button does ?

Thanks.