FWIW, all the cracks look old, There is nothing looking at the crack that it is new. New cracks have their own "look" about them. Perhaps they were just overlooked before. These are typical cracks from settling.
About the posts, this is typical of older construction. New construction would have used pressure treated wood to isolate the wood from the concrete. The first pic show newer wood being used as a post that should or could have been treated, but there is no discoloration suggesting any deterioration or even beginning to. The angled post appears to have been a temporary post used to jack up the beam to add the post I was referring to.
Nail pops are also a very undesired thing that happens as well. It is not structural, only cosmetic. Curious how it is showing now, unless they have been there since the remodel, if the walls were redone. Never the less, they have been there for a while too, not necessarily since 1948. The nature of the paint reveals that.