Unplugging the fuel pump relay while the engine is running is an effective way of minimizing the fuel pressure in the system. You will spill some fuel no matter how hard you try to avoid it. When I changed my injectors, it took me about two hours. Take your time on the fuel injector electrical connectors. They may be tough to remove. I popped the cover off of the fuel injector harness housing and then removed the injector connectors. When reconnecting, having the top cover off will allow you to seat the connectors firmly on the injectors. Also, don't forget to give the area around the fuel injectors a quick blast of carb cleaner or compressed air to remove any loose debris.
Your engine will run better when you replace the vacuum line. With that broken line, you have a vacuum leak. Check your other vacuum lines for cracks and tears too.
HTH