actually, some places do sell pods...but yes, they generally are prsent in your tank just often in small numbers due to predation
the 4 nassarius snails is probably not going to be enough...i would look into getting maybe 5 astreas and definitely some of those reef hermits should be ok. i think the problem kahluazzz had was his choice of hermits. the big ones tend to be ackward and problematic in reef systems in my opinion