Hi, the apple snails and the big guys you see in the pet stores reproduce sexually, so they are unlikely to overrun your tank. ghost shrimp are fairly easy to care for, you have to make sure they have a place to hide while they are molting, but other that that - I can't think of too mant specific needs. They are fun to watch too. However, they aren't great algae eaters. YOu might consider instead amano shrimp (also easy to care for) or otocinclus catfish.