"I may need some suggestions on stacking it, also I have nassarius snails when I add all this rock to the sand bed do I need to dig them up or will they find their way out if I cover them?"
Stacking base rock is straight forwards, although, achieving that desired look could be tricky. As with all base rock, do a rinse and soak in r/o-distilled water prior to placement in the system. This is what I do. Select the three biggest pieces of the lot. I start in the center of the aquarium, selecting the most desirable piece as your focal point. The larger, the better. This serves as an anchor point as to where you will start to build outwards. Try not to lean pieces against the back wall, tight against the back-bottom corner or along the sides of the aquarium. This will create dead spots in the tank and make exportation of unwanted material that much harder. Work you way outward from the middle by placing a few smaller pieces, a few inches away from the middle, lateral to one another and place a larger piece across the span. Do this to both sides, intermingling sizes to create various formations. Cap the ends with the other 2 largest pieces for anchors. When spanning a gap, place apiece securely against your inner bracing; pull the piece it is to be placed against away from the articulation point and interlock with the weight of the outside anchor pressing firmly against it. You will have to spin, turn, up-end pieces so that they all interlock without the possibility of slipping, teetering or worse case scenario, tumbling over. A firm wiggle after you place them will tell you if they are secure. If you're having problems securing your aquascape, your base rock should be malleable enough to chisel or cut (dremmel) to secure your rockwork. Drilling out extra holes, in prime location on the rock, will also give you more options as to where you want to put newly acquired specimens for your system (feather dusters, corals, shrooms...) and extra hiding places for smaller, more fragile species of fish you may acquire in the future. Just take it slowly and don't forget to immerse/rinse afterwards.
HTH & Good Luck
BTW, if your concerned about your snails, a new kitty litter scooper might help in locating buried snails, but personally, I think that they will do fine even without your assistance.
