This is a do-able DIY job providing you have a few basic skills. You would first have to remove the old box and cut out enough sheet rock to have good access. Keep in mind, it is just about as easy to repair a large hole in sheet rock as it is a small one. Cut it out to studs. There is a box with a single lever shut off for both hot and cold and a 2" drain outlet that would go it the opening. The plumbing would depend on the kind of pipe you have, and that does not show in the photo. Copper would be easiest, but if it is galvanized, you would have to use elbows, nipples, and unions to fit the pipes to the valve body, and make the connections to the existing pipes. As an alternative to that, you could transition to copper first, then use copper to complete the connections. Certainly replace those hoses with the braided stainless steel. Fill in the sheet rock after everything else is finished. It's not a really complicated job, but it does involve a lot of cut and fit work. Having the ability to sweat a copper joint would be a big plus. As Jimbo pointed out, you would save yourself a lot of piddling work if you hired the plumbing part done and of course a plumber would take half an hour to do what would likely take you all day.