[Cob] Newbie w/ Questions about 1st project

[littlehouseantiques at att.net]

Hi, 

A newbie to this list and to cob (what absolutely glorius stuff!)  

I've read and read and read and finally got tired of reading and started doing!

The "doing" has answered some questions I had, but has (of course!) prompted even further questions.  
Could I presume upon the expertise of those in the list to help a newbie out and ask a few Q's?

I've starting building a little "test" wall that has a foundation trench 18in wide x 6ft long & 6in deep filled with gravel, upon which I laid dry stones in 3 courses about 8 in high, battering them until the top course measured 12in wide.  The foundation is slightly curved (in other words not a perfect rectangle and it is situated on a slight slope (along a slightly S shaped downhill path) so, to provide really good drainage (which I particularly needed at this spot) I also continued a smaller trench (6in deep x 4in wide) on down the slope to carry the water that accumulates at the bottom of the foundation away on down the hill.  For a visual of my project go to:  

http://community.webshots.com/s/image17/0/5/29/186600529lPstaL_ph.jpg

Okay, then I started cobbing and thus far I've got about 4in of cob added to the top of the stones, so my "wall" thus far is about 1 foot high.  The "plan" was to continue building this wall up and "practice" making openings in the wall (open air windows, etc.) and to try my hand at sculpting flowers vines, etc. and to cap it all with some sort of mini roof (slates?tiles?).   Well....when I got to the 12in point in  overall height, I started thinking, what a perfect spot for a garden BENCH (it is along a garden path done with hypertufa stones and moss) and so my mind at this point is turning over ideas on how to "weatherproof" this thing withOUT erecting a roof over it.    

Also, how to make it so that when weather is damp outside, when you sit down on it, it doesn't leave one with a muddy rear end (lol!)

Initially I thought, that laying down hardware mesh and simply hypertufa-ing over it to make it look like stones was the way I'd go, but if I understand things correctly the tufa will soak moisture in and transmit it down to the cob so I'm thinking this won't work...

Or would hypertufa stones work as long as I laid a piece of plastic over the top of the last layer of cob?   

Or perhaps simply sealing the tufa to make it waterproof would do the trick?  

I know I could lime plaster the cob...but I'd rather NOT mess about with lime if I can possibly stay away from it.  

Any and all advice would be very welcome!

Kathy