He has a lot of old blocks lying about his place. The block below is 1.2 cubic feet. When purchasing a block, be sure to tap it with a hammer. If a crystalline ping is heard the block is solid, but if a dull thud is heard the block is flawed with a crack. Limestone is relatively soft and can be scratched with a key.
Limestone is a Sedimentary rock and therefore is layered horizontally.
When carving sculpture from limestone which is to be displayed outdoors, the sculpture will weather better if the layers are kept horizontal. Shells and fossils are embedded in limstone and can cause surrounding stone to break off when carved but generally they're workable and not too frequent. The paint prevents the pencil from rubbing off during carving. The primary view is roughed out with the hammer and pitcher first. The purpose of the pitcher is to remove large chunks of unwanted stone very quickly.