Look at athe
SerialPort[
^] class - it will handle the communications, though you will have to work out how the uProcessor wants the data and format it appropriately.
To get the GUI position, try handling the
MouseMove[
^] event- the MouseEventArgs parameter will give you the mouse location.
However, I can't remember if MouseMove fires for a form when the mouse is over a control - it may fire at teh control instead. If so, then you will have to handle the control MouseMove event as well and may have to translate the coordinates from local to form based. Not difficult, but it may be necessary.