Their methods are the following: they jack up the house to get it level and use some type cement cylinder as support, in this case since it is pier and beam, below the supporting piers (or slab if it was concrete).The costs depend on how bad the ground is and how many cement cylinder they use. 

A few days after the couple moved in, the stairs caved.

I'm looking for someone to do general stuff like new floors, painting, fixing cement steps and replacing some baseboards. 

They were taking pictures and measurements of the outside stairs to the 2nd floor unit. 

The new block foundation was secured with re-bar and cement through the center of the blocks and a new 2X6 frame was built on top of it to support the house.

How about tearing it down and putting up more of a set of stairs with a small landing at the top.

That cement path that wraps around the prop and the walk way toward the door... if you have enough, perhaps brick those.

I would get a floor grinder and sand down the top coat of the cement.

I added a door to the stairs to separate both units and added a kitchen to the downstairs unit What was the outcome?

So, a quick rough estimate of my expected usage: portland cement to water ratio is 2:1 with no aggregate added, foam to slurry ratio roughly 4:1.