Yes, a ten gallon is ok for inverts. Just keep in mind that a tank that small needs constant attention because even the smallest flux is gonna make a big impact. And, since inverts are more sensitive than fish..... you get the idea I'm sure.
If your intent is to just add some crabs, snails and shrimp for now, 1lbs per gallon is fine to get started. You can always add a bit more as you go. If it were my tank, I'd put in (once the tank is fully cycled of course) maybe, hmm. An emerald or strawberry crab, maybe a hermit or two, some nassarius snails, a feather duster, a pair of cleaner shrimp and some algae eating snails later on once the tank gets some algae. The cleaners would be your centerpiece inverts and they are really entertaining coming to the surface to eat and being very unshy.