Re: hard to move windows
1]When he installed the windows , he may have shimmed them to tight. It's probably better to be a little tight than to loose. You may be able to loosen the shims.
2] He may have used expanding foam to insulate around the windows which expanded and is forcing the sides in against the sashes. You might be able to cut some of the foam out next to the window.
You might try rubbing some paraffin in the tracks.
Be sure you live your life, because you are a long time dead.-Scottish Proverb