From the picture of corroded steel bar,water sip into the concrete making steel reinforced bar corroded, once steel corroded, it expand and crack the cement from inside out, this is a serious issue.

Main root of cause, porous cement.

For 1 picture, land compacting/sink could cause similar problem as well, whereby you beam got pilling, so sink little but your wall is just sitting on non-pilling floor, sink more, so crack of the wall appeared.

Just my shallow knowledge in it. Feel free to correct me if I am wrong. I am not civil/building engineer.

Further seeing it, there are some large 'stone' in the concrete exposing piece by piece.

Sorry I am not civil engineer, don't know it is norm to see cement peering off then exposed the stone or can see the stone one by one with so many in the last picture.

There surely got stone and sand in the concrete if not it is not called concrete anymore, but seeing the stone piece by piece exposed like that is kinda not normal. I could be wrong.

Yes, the most important issue is the steel reinforeced bar corrode, it is the main load carrier. Corroded steel bar mean lesser diameter to carry load while if the corrossion penentrate into deep area of the diameter, then it cannot properly stand the load.