Why did Gromit change the knife?

We are shown how Gromit caaarefully selects a knife, to cut .. *gulp* .. a carrot to slices.

But then we are shown a table filled with plates that have lots and lots of carrot slices already.

What did Gromit use to slice the other carrots, and why would he change the knife for the last plateful?

Why even use plates, if you're going to dump the carrot slices down the 'feeding tunnel' anyway? You could just dump the slices straight down without all those plates.

Also, carrots are very bad for rabbits, so are they trying to poison them?

Why even slice the carrots, when rabbits have teeth anyway?

Why don't things ever make sense in movies?