Yes the widget code you saw in the functions file is what registers the widget areas to exist, and the location of those widgets on the home page are determined by the position they’re located in on the home.php file…..and the css as well. So if you enabled or created new areas, you would have to either edit the existing css or add css in order for it to maintain the responsiveness.
My rate is currently $100 an hour for custom modifications. Something like this shouldn’t take any longer than an hour for sure. I’m guessing other developers would charge around the same. Before you hire anyone, take a look at some of those tutorials to see if you can figure it out.