Giant african land snails are tropical animals and there for will most likely need a heat mat as well as high humidy but the exact ranges vary from species to spesies. 

The heat mat can be placed on the side or on the bottom of the enclosure but there should be a temprature gradient made. This means that the heat mat should only cover half of the bottom or one side of the enclosure. There is some disagreement about placement of the heat pad with some sources saying that heat mats should not be placed on the bottom of the tank becasue it could lead to snails getting harmed when trying to escape heat or that it could dry out soil but other sources claim that it is completly safe with no issues.

In addition it is important to use a thermostat to make sure that the temprature is consistant or held within a specific range 

In addition all GALS are hemaphrodites meaning they are both genders and are able to fertilize themselves if another mate is not avaible. The amount of eggs can vary from species to species but some lay 100 - 500 eggs in a single clutch. The incubation period on these eggs is also very small being only one week. Therefor it is recomended to fluff up the substrait of GALS once a week to check for eggs and make sure it isnt too compacted.

To get rid of the eggs you can crush them or freeze them. Then they can be safely thrown away or fed back to the GALS since the eggs have a high amount of calcium and nutriants 

GALS need a varried diet with a few specific spesificaitons. 

GALS need calcium and food always avaible. Calcium is important for shell health, if a calcium soruce is not avaible it can affect health and growth

Food should also always be offered. Snails are able to portion control normal foods and may have need through out the day but as they mature they will not need food daily but it still should be offered. 

More info about specific foods can be found HERE