Nice so he did have a cameo.
I'm guessing that in TOS they had a hydroponics bay so the likes of Nurse Chapel could make her homemade Plomeek soup for Spock and that the food slots chucked out basically cubic vitamin pills.
As for vegetarianism, I think it's a case of where you draw the line with replicators, at some point an animal will have been killed to provide the pattern for the replicator to use, so would it be against a veggies morals to eat replicated meat?
Makes you wonder, that in the 24th century with all the technology, could they not just grow meat from stem cell cultures without having to kill an animal at all? Just food for thought (sorry).