Can you use queso fresco in a cheesecake?

Yes you can. Google (or Bing :)) Queso Fresco Cheesecake and you'll see recipes. Because of it's slightly sour note like feta it would probably do better in savory cheesecakes but you can make a sweet cheesecake from it. Most recipes will call for cream cheese to get the consistency most want. You can make cheesecake from most any cheese combined with cream cheese.

I wouldn't. Typically, cheesecake is made with cream cheese or ricotta.

Not as the only cheese. You need another cheese -- cream cheese typically -- to provide the creaminess which the queso fresco won't give you