Building on rock

Hi all,

I have been looking at land in South Australia, that is on a slope however most of the core excavation is complete, with a flat area to place a house.

The agent doesn’t know a lot of history of the property so I asked the big hours who advised the last owner commenced excavation but stopped offer hitting rock and breaking the machinery. They ceased with their plans to build. The rock is visible throughout the propert

I am wanting to place a modular home on the land (but am yet to put in an offer).

The price range seems very high and it has been on the market for quite some time.

1) is it difficult to build on rock?
2) is a slab or steel posts best?
3) what tests are recommended and added to part of the conditions of my offer?
4) knowing the history is it best to add that to my offer due to the challenges and costs I offer less than the price range?