After reading through this thread debating whether to reply I thought I would reply with references from primary literature.
As found by Webb (1982) the most important prey of freshwater crocodiles was aquatic and terrestrial insects, fish and crustaceans. With an increase in crocodile body size an increase in the proportion of aquatic prey was consumed. Vegetation was found in 39.9% of crocodile stomachs, parasites were present in 43.8% and 88.2% of crocodiles had stones present in the stomach.
A study by Garnett (1986) on parameters affecting growth of saltwater crocodiles in captivity concluded that diets of pork and beef were superior to fish.
Webb (1991) found that the average juvenile diet of saltwater crocodiles is characterized by 70-71% water, low fat levels 3-4.5%, high protein content 12.7-14.7% and Ca
from 7:1 in animals 300-599 mm TL declining to 2:1 in animals 900-1200 mm TL. Captive crocodiles mean food conversion rate is 17-40% as compared to wild counterparts of 82.4%. Wild crocodiles require food equivalent to 4% of its body weight per week while captive crocodiles require four times that amount (16% body weight).
Now to give my personal views. A varied diet is always best, for juvenile crocs I would feed twice a week on crickets, pinky mice, beef heart, beef liver, kangaroo mince (with vitamin and calcium supplement mixed in), chicken, yabbies, freshwater shrimp, small feeder fish (rainbow fish). If you want to get more technical about dietary components then use the above references. In regards to stones, crocs ingest stones to help in mechanical digestion in the stomach. In regards to vegetation present in stomach content I would assume the majority is ingested during prey acquisition, but I have known one juvenile salty to tear up and consequently swallow two water lilly plants over the space of 6 months, whether this is relevant to diet I don't know he was just a cranky boy.
Oh and yes I do have experience in crocs
References:
Webb, GJW, Manolis, SC and Buckworth, R (1982). Australian Journal of Zoology, 30, 6, pp. 877-899.
Garnett, ST and Murray, RM (1986). Australian Journal of Zoology, 34, 2, pp. 211-223.
Webb, GJW, Hollis, GJ and Manolis, SC (1991). Journal of Herpetology, 25, 4, pp. 462-473.