I have a skirt suit w a jacket that buttons up too high. Would it take extensive alterations to make it so it buttons lower?

That should be a very minor alteration.

The button holes can't be moved, so they would leave a mark. I don't really understand what you mean... how can you move button holes? You can make NEW ones, but the old ones will still be there.

Maybe not. They'd remove the top button and press the lapel down so the button hole is hidden under the pressed down lapel.