in reagaurd to the grinding.
if it is just a quick little grind, as you put it in reverse, thats normal, the only thing you can do about it is put it in another gear, then reverse. reverse doesn't have any synchros so you are forcing the gears together.
as for the clutch, if you are looking for performance, then you probably ought to change it now, but if all you want is for it to last, then don't worry about it until it starts slipping. My accord has the factory clutch with 180,000 miles on it. and it still holds strong. if I rev out and kick the clutch it slips, but thats to be expected.