I don't think so. Mine is straight through with no strainer or scoop at the hull. The scoop might help defelect eel grass and other debris however. I do have a sea strainer several feet inside the hull.
You don't need a scoop for proper water flow,but you should have some kind of strainer on the hull.I have seen all kinds of things caught in hull strainers,plastic bags,gloves,eel grass,sea weed,bird feathers,and anything else that's floating around.If this stuff goes up inside the seacock it could cause all kinds of problems,including jamming up the valve so you couldn't close it,not to mention closing off the supply of cooling water.
I have seen both ways.You can use self tappers if the hull is thick enough.I would just bed it on with some 4200.If you thru bolt I would glass over the bolts inside.Some of todays metals aren't of the best quality,it would be better to be safe than sorry.