Relocating Staircase

Hi all, I am new to renotalk having just bought a terrace and planniing for a&a. I have so many questions at this planning stage. One of my questions is on the cost of relocating the stairwell to the side of the house and installing a anew staircase. The present staircase is located in the centre and eats into the narrow width of the house. The area in front of the staircase is inefficient because it cannot be used. Moving the stairs to align along the length will make better space usage. Has anyone done this before or considered this , and do you know the costs taking into account the demolition, the construction of new floor space at the old stairwell and the costs of new staircase? Any input would be deeply appreciated.

Another question I have is the cost for soil test for one location on the land. One builder said $3000. Another said $2000. Another said a few hundred dollars. Does anyone know what is the market rate.

Thanks so much