Hi Jose,

To close the InfoPath application, not just the form, you need have a fully trusted form.
Once you have that you can access the Application.Quit(false) method call within your script.

An alternate to closing the InfoPath application, and therefore not requiring fully trusted forms, is to select the option
to "Close the Form" after submitting to your server. This is an option selectable on the Submitting Options screen in the Submitting forms dialog.

I don't think you can change the size of a control like you are asking for.
This might work for you though...

Insert an Expression Box under the Drop Down and link it to the Drop Down
field.
Drag the width to be the full width of the screen (or the widest you will
need).

Set Conditional Formatting on the Expression Box to hide it, if the length
of the value in the Drop Down is Less Than the number of characters that
show in your box.  You expression will look something like this:
string-length(my:field1) < 15. and then "click Hide this control"

So, if the selection in the Drop Down is "Ford", the Expression Box will not
show. If it is "Chevrolet - Monte Carlo", the entire entry would be
displayed.