We have an overhead shower rod for our claw foot tub (D Style) and some screws where it attaches to the side wall are coming loose. I have not been hanging heavy wet items on the shower rod, so I'm not sure why this is happening. The shower rod is chrome and still looks good, but the screw heads are rusty. The bathroom wall is dry wall applied over plaster (I think). What is the best way to replace the loose screws in the wall?

Our home was built in 2013. Although we chose everything from the floorplan to the doorknobs, we knew very little about construction and it was a steep learning curve. Five years in, I'm left wondering if every little kink is either part of the normal aging of a house (with 2 toddlers living in it) or a sign of poor workmanship. One of my biggest concerns right now are small cracks that I've noticed in a couple of walls (see attached photos). One is at an arched wall between two rooms, and another is along a wall just below the second-floor landing. Most concerning is that these cracks are also beginning to show between the wall and the stairway. Is this normal? Is this a sign of deeper issues in the construction? And what is the best way to repair it? Is there something we can do to ensure this isn't happening every 5 years, but is instead done right? Thanks in advance!