Apple snails need 10 gallons initially with 5 additional gallons for every additional adult, most species are plant eaters except for bridgesi which are fairly common and are non live plant eaters, they may breed if you get a male and female and lay their eggs above the water and they do wander but only if they are not content with their environment.
By zebra snail I assume you mean a nerite which need 5 gallons initially and 3 gallons for every additional snail, they only breed in brackish water but can live in freshwater, don't eat plants and may go for a wander but only if not content with their environment.