Having just completed the structure of beautiful superadobe domes, I am compiling information to determine the best methods and recipes for finishing the exterior.
The climate here tends to be humid and hot, although the winters are cold and rainy (not freezing).  I live in Uruguay.
So far, I am intending to use earthen plaster scratch coats after -removing the bags-. (Is this in your opinion necessary?)
I will include horse manure in this mix and also fermented cactus juice for the hydration. The soil is high in clay content and we will add to this sand.
I also intend to finish the outer layer/s in a lime plaster and also hopefully sodium silicate, which I am currently attempting to source..
I am also considering using the "reptile" segmentation at least for the very bottom meter or so of the walls.
Cattails in the final plaster layer yea or nay?
I am looking for advices here.
I would also like to create as much water catchment as possible, with rain barrels.  To this end I may want to sculpt gutters into the plaster, but of this process I am very unsure.
I am open to all ideas and suggestions; please share.

I have to ask, before you started did you have any idea about these questions?
Gutters need to be formed as the building is going up, its much easier then.
You can leave the bags, but the outer layer needs to be thick, 50mm at least to ensure the new payer does not peel off.
Horse manure and even a bit of straw will help and as you get closer to the final surface, less straw is required.
Experiments with different ' brews' for the coating are a good idea.
A lime plaster isthe best method

Hello John. Thank you for responding. Yes, we had some idea of these questions..some and not all things figured out. I will try to post photographs today. There are two layers of three small circular windows, near the top, which will allow for guttering to be shaped in/as the spaces between. Catching water would be potentially beneficial, but is also not entirely necessary. Where I think the water will be most needed, is for the fruit trees, during the 'dry season'. (This summer we have had a lot of rain and many chilly days and nights.)
At least in the beginning, until we can sculpt the land for water catchment, holding rainwater in barrels for these trees would be great. Thus I am trying to see if it is feasible. Honestly, the structure was built more quickly than I thought it would be. The first thing that we did was to dig the entire area down to about a meter deep and backfill with large stones and sandy well-draining earth..build the foundation layers of bag and fill a bit more inside and around, thus water should easily flow down and away from the house.

What rainfall per annum do you have?
Water under the house may 'wick' up through the material you have placed inside the foundation. It is prevented normally by laying an impervious layer, IE Plastic Film

Anyway check that.
What sort of barrels do you speak of?
Watch the cost of barrels compared with purchasing a larger volume tank for the same money, it is a trap many fall into.

Thank you again, John. Great questions. As for barrels and a larger water tank..we have one of those also..and all are being reused in great condition. Barrels vary, but are usually one of two types which are plastic with screw-on lids, or metal with a "food-safe" coating inside. I think the plastic ones are preferable for water collection. Right now we are getting ready to begin plastering the exterior. The average annual rainfall is approximately 960 mm. Our foundation ought to be super for keeping moisture flowing away, as it was dug very deep under the entire space of the house and backfilled and also built up a bit to create flow away. We have sealed the base levels of earthbags with an "impervious" plastic layer, but do not intend to use one beneath thecflooring, rathering to  create a capillary beeak with larger gravel and work up to finer layers, includingbrick dust, whic we also have obtained for use in the plaster. We will also bury some tubing with holes and fill around with medium sized gravel etcetera.
We have procured what is simply labelled "cal hidratada" and "para revoques", for plasters. It says 100%. And this seems to be the only type available here. It is in powder form. Although you can also buy a liquid solution used for lime washes, usually in smaller bags. These bags are 20 and 25 kilos.
We have two grades of river sand, and red brick powder is on its way. The idea is to also finish this with waterglass, which we will be ordering soon. We have one very furry dog and one less so, who have agreed to contribute fur for strengthening fibers. I have yet to consult the baby horse, but I will chat with him today and ply him with carrots.
And how could I forget?¿ Fermented cactus juice.

Also, posting photographs seems not to be possible from my device. Maybe I will post some from a neighbors computer.