I have a few different varieties of Sulawesi snails. I have one of the black coned yellow snails that you are talking about mattlee, and I also have a couple of the yellow/brown coned snails that Kiriyama has.
My black shelled yellow snail that I have is quite mellow and less active compared to the yellow/brown coned snails. The black coned snail will eat algae off the side of the glass, and I did catch it eating part of my java fern plant that I had, but I think that was more due to the minimal feedings I was doing to get rid of a parasite/worm thing I had going on. Since I have been feeding the shrimp/snails regularly again with algae tablets I haven't seen him eat any plants. However, my brown shelled sulawesi snails are always munching on any greenry they can, and they eat my bogwood, too! Occasionally all of the Sulawesi snails will go into a 'hibernation' type mode where they retreat into their shell for a few days. I haven't quite figured out why all of my Sulawesi snails do this. I also think that the black coned variety snails like a bit more current as they like to climb up the side of the tank and hang out around the filter output, maybe because that area has more oxygen or they just like the current, I don't know.
All in all, they are really easy to take care of, pretty hardy, and in my experience most of them are pregnant when they are brought in from the wild. Out of the six or seven I have had, two have died, for unknown reasons, and three have given birth a few days after I brought them home from the store. They give birth to only one snail at a time, and they do give birth and do not lay eggs. I have researched online Sulawesi snail breeding habits and have found only one occurrence of snails breeding in captivity, mine haven't reproduced at all.
I tend to ramble on, so I apologize if this was too boring and too much info. I do like my Sulawesi snails, they are quite interesting creatures, and I find them cute.