Generally it'll be on the top only unless you use a suspension base. Add about 1 Tablespoon per pound of m&p soap base. It should be added when the base is nearly melted, right before you add your fragrance.
They have pretty soaps. Yes, I see the soap you want to dupe. http://bombcosmetics.co.uk/handmade-soaps/cast-away-sliced-soap-boxed
They make it in a loaf mold and then cut the slices. Maybe the shredded coconut is added afterwards? I'm not sure.
It's a thin layer of coconut, especially along the sides, which means the exfoliating properties won't be there after using it once or twice.
No, you can't do that because once you can cut MP it is not "sticky" nor wet and there is nothing for the coconut to stick to. Again, coconut will turn brown and/or moldy and while it may look pretty for a little while, you certainly would not want to gift it or sell it because you would end up with a soap someone might be afraid to use for that reason.