Current methodology does not take into account evapotranspiration from vegetation, the ground or water features. Few methods out there exist for evaluating the effect of evapotranspiration on outdoor comfort. Envi-Met is probably the most established and ready to use solution. Others suggest to tightly integrate it with CFD to get high accuracy: paper
I wrote my master thesis on the subject and tried to integrate the effect of evapotranspiration in a Ladybug Tools work flow. As you are the second one asking about evapotranspiration this week, I probably should take some time and make a tutorial for demonstrating my thesis. I discussed this topic with @devang earlier this week: post
As for your question about the soil types: My guess is when you change soil in EnergyPlus you just change the albedo, heat capacity and heat storage of the material (density is an important component in this). This should lead to an effect similar to the UHI. That the temperature is just a little higher during the day, but the temperature doesn’t decrease as much during the night because of the higher heat capacity/storage.