Wait until you have mastered your small tank. It typically takes about a year for a tank to become fully established.
For now you need to run your tank fallow for 12 weeks to kill off any remaining ich in the tank.
Those are collonista snails. Awesome little grazers that come out at night., bonus...they breed well in captivity. They don't get any bigger than what you see now. Populations tend to explode then wane due to the availability of food.