PB, your side yard is 5ft. what is the depth?
How long before you plan to sell?
Portable? Is it to be a one time move?
How much do you plan to use it and for what purposes?
As for first course (solder bricks) above or around floor bricks, this also depends on what you want. Some of us want it around, like myself, some build on top. I would think that if you plan to move it, build it on top.
Below the floor bricks it is becoming more regular to use insulating boards, whereas you can use vermiculite type material as an option as well.
I just wonder how long you will live at your current place, and how much you plan to use it because you can erect an inexpensive, temporary type oven to get you through for practice. Once you get to your new destination, plan out the area, and size of what makes you happy for an oven. You can see a variety of ovens here that fit the surroundings, and they compliment the usages of the builders.
Now that I have assisted with some of the questions you had, I hope that you will elaborate further on some of this.
Robert (Richard, Frank, Sam, or whatever I am called now
)