can I add a navigation and backup camera to 2013 ford fusion
Sure all it takes is money . But for Navigation a portable unit is best because you can take to the next vehicle you buy . The backup camera just do like I did and use Google to find places near you that do that or find ones you can install yourself.
One important consideration is how the dash is laid out. I added a great update to my old Highlander. May I suggest that instead of your Nav add plan you consider this approach? It achieves the nav for much less money.