No it can not. Toothpaste as name states is for teeth, get the proper acne meds to treat acne-;).
No. No. Toothpaste only belongs in the mouth because it can burn your skin. Use an astringent that has salicylic acid in it.
No. But if you try it you can see how easy it is to get a chemical burn on the skin. The redness and eventual scarring it can cause in areas where it is used deters most who try it.
Get a real Rx. This is the 21st century. If topical benzoyl peroxide 5% 2x/day hasn't cleared you in two weeks, get prescription-strength treatment from your physician. The medications for all but the most severe cases are inexpensive and safe.