Unfortunately, for certain parts of MIndanao like Cotabato, Zamboanga, and Marawi City. In my opinion, I wouldn't call them safe especially for caucasians. But you should have a great time in Davao, nobody messes with the Mayor there (He is like Dirty Harry/Wyatt Earp rolled into one) and his posse is called the Davao Death Squad It worked for Davao, very low crime rate
As for the tourist visa, I don't think you would encounter any problems, our country needs tourists