This is a great place to take your kids. I took my little cousins here and they are always asking to go back. Make sure you bring lots of carrots and other veggies to feed the animals-- you'll run out fast!
I've never heard anything about horses biting children. Maybe the children got nipped while feeding them. It's really up to you to be careful (just feed them veggies that are larger in size/length). Do you really think the animals know better? All of the animals here are friendly and calm-- except for the sheep and goats when they are pushing each other for your carrots.
As for the two dogs wandering around the area, they are the most docile dogs I have ever seen. They just roam around together and don't make a fuss at all. Even for those afraid of dogs, no need to worry about these two-- unless you are flashing treats in front of them or something, they will leave you alone.
For a free petting zoo, this place is pretty amazing and well worth visting. A great afternoon activity for the kids.