Because the fork is the thing being given. "To whom?", one might ask. To me. So, it is "Bonvolu doni al mi forkon", or in a different translation from the one up top "Please give a fork to me". "Bonvolu doni forkon al mi" would be the same thing too
Yes, but then you'd have "Bonvolu doni min al forko!" - "Please give me to the fork."
The -n is for whatever is being given. The al is for whoever receives it: "Bolvolu, al mi doni la forkon." - "Please, to me give the fork."