Not never
Just not very often in summer and not at all in winter. Rule number one should probably be that it dry out completely before you water again, that will stop you overwatering too badly. That should take no more than a few days in summer or your soil is too soggy, use plenty of grit. Use a loam soil, not an organic soil.
If you have a mature specimen, anything more than a couple inches across really, then you can rest assured that they could last your whole summer without water if they really had to so the only thing you will do to hurt them is give too much water.
Full sun and as much heat as you can find. Are you in the mountains? A greenhouse will help. Down round Atlanta and south, just being out on a nice south-facing patio will be warm enough.
E. horizonthalonius is hardy down to below 20F, maybe 10F if completely dry. The skin may mark in cold humid conditions. Its probably best to keep it above, or only slightly below, freezing in your climate.
