Congrats on your new land! And on wanting a Rocket Mass Heater!
First thing, if you want to build a rmh . I highly recommend getting a copy of the Rocket Mass Heaters Builders Guide. Written by Ernie & Erica Wisner, it is the go to book for all new builders. Easily available from Amazon or from them directly. It will be the most important thing you can buy for your project. It will teach you the correct terminology, keep you from making rookie mistakes and answer quite a few of your questions.
OK , your tuff shed has a laminate floor. First off you must make sure the floor is supported adequately. Blocking / support under the entire rmh is critical. If your floor sags your rmh breaks in half ...
Now that your floor is supported you must protect your laminate. Start by laying clay bricks flat on the floor, separated but close , they are there to fully support 1/2" hardy backer board (cement board) that you lay on top.Your rmh is built on the cement board. the bricks support the weight and provide the needed air space to keep from overheating your floor.
Now you must decide what size RMH you want 6" or 8" (in Utah I recommend an 8"). Then you must decide if you want a conventional J tube rmh or a batchbox rmh. Next you must decide if you want pipes thru a bench or if you want a stratification chamber rmh (brick bell).
As you can see there is a lot to figure out ahead of time. Start by supporting your floor and ordering the builder guide.