experimentation cob!

Hi all!
I posted recently about a small ~200sqft building I'm using to experiment with a few natural building techniques since I'm new to a lot of this.

I've done a lime plaster on the exterior walls and straw + clay insulation in the roof bays. Next, I'd like to cob the interior floor over the cement and round out the corners to give it a more organic feel.

Doing research about cobbing over cement foundations, I've seen some folks recommend incorporating a perlite layer first to make the ground softer.

This is an intriguing idea, because I'm planning to make a little batch stove in the corner and I've seen perlite used as a preliminary layer.

Basically, I want the floor to feel nice, look cool and be prepped for a batch heater when I have the time to stack bricks and make it happen.

Any recommendations or step-by-step guides about this?

As a bonus, any suggestions about what to do to finish the roof? I was thinking cement board + lime/sand mortar then finishing with a pigmented lime putty, but I'm open to any and all ideas. Just trying to have fun with it and learn some techniques!

Pics attached. Thanks (:

I would consider perlite as the insulator from the foundation and not so much as a long term shock absorber.

I'm not a cob expert by any means, but I have made a bunch of it for RMHs.
Where you want your batchbox to sit, you will want a minimum of 4" of perlite for it to sit on; 6" would be better.
The massive heat radiating off the bottom can / will destroy your concrete if it is not well protected.
Build a box 4" - 6" deep, large enough to hold your batchbox core.  (The bell does not need extra protection as heat is lower and ash will insulate it)
Put a shallow layer of cob in the bottom, fill the rest with perlite / dry fireclay, and add some water to firm it up.

Pouring perlite on concrete before cobbing sounds like overkill to me, but I'm not a cob builder.
Good Luck with your project, and keep us posted with many pictures on how it is progressing.