U.S. Shell, Inc. US Large World Mixed Shells, 1 Kilo weight

How big are the shells? Approximately how many per bag?

I am looking for empty shells for my dwarf blue hermit crabs for saltwater tank so they need to be between 1/2" to 1 -1/2 inches. Are these ok?

Just got this order of shells. Are they safe to put in an aquarium or do I have to treat them

Are these pretty for a bridal bouquet or no?