I'm planing to do a shelly tank in the near future so I have been doing my research. From what I understand they not only need shells but also need a sand substrate to be able to bury the shells and move them about.
Might be a good idea to pot the plants, as wicca27 implied. Otherwise shellies are generally harmless to plants, though as stated said digging tendencies need to be allowed to be expressed...might want to decrease the shell pile.
Paracyps and small cyp species would most likely be fine in that tank, and if you buy a dozen or more may even spawn for you eventually. I'm not aware of either of these genera bothering plants.