Berber Skink help? and some other questions?

cant help on 4,5,6 but 1 i think they would. 2 i have 2 berber skinks in a 20 gallon tank for the past 3 yrs. 3-sand rock plants? hydrometer and thermometer water dish and i feed them calcium dusted crickets every other day....7 www.LLLreptiles.com.