Hello, and welcome to the forum.
As for the sink, I assume you have an enameled sink, and to fix a problem like that, all you can do is replace it. You might consider using a double stainless instead of the enameled.
The backing out screws, drawer slides failing, runners being too short, most of that is caused by bumpy roads, lots of towing
etc. If you are having plastic hangers reaking at the end of the runners, it is possible to build supports for the runners at the back of the cabinet out of wood. Then put new plastic keepers in abd all will be well.
The ball bearings coming out of the couch is something I've not experienced. Maybe overloaded?
There will be more responses from much more knowledgable than I am.