Greetings good people

I have a small plot in Ongata Rongai in a place called Kware along Gataka Road. It is an 1/8th and i want to do single rooms as i wait to get means to do a better project infuture.

I want to do single mabati rooms. How many can fit and how much can i expect to reasonably spend on foundation ?

I also want to do a good and big septic with the future development in mind. How much can i expect to spend on it ? digging e.t.c

Thanks