There is no difference. For example, part of my company involves rescue equipment. For some specialized products, we buy an original item, it is modified, and then resold. We are not violating any laws since we are not creating a protected item from scratch and are not depriving the original manufacturer of profit. There is no difference between this and motion pictures.
Upgrading equipment and altering a movie aren't the same thing. If you presented yourself as the original developer of the item, however, and put it into production violating any patents, you probably would be in trouble, but again, that is an entirely different issue.
Irrelevant. That falls under patent protection.