Will any update from Apple solve all problems stated on this board?

In general, no. There are a few exceptions. Updates are there to improve upon existing specs, offer new compatibility with new types of software and hardware, and improve security features of the operating system. The problem faced with these sorts of updates, is that if a third party didn't follow specs well enough to begin with, then they have to update their software, drivers, or firmware to catch up! So instead of expecting Apple to fix wireless issues with specific third party routers, or expecting Apple to fix compatibility with specific non-Apple applications, you should perform updates with care by checking that any software and hardware you depend on has been tested with the update before attempting to upgrade. You should make sure all your software is free of corrupt files, directories, and permissions. You should make sure all your hardware is performing flawlessly as is. And only then, backup your data at least twice, and upgrade.

Too many people come onto this board complaining that update XYZ killed their machine. It did not. I've updated to every operating system, and if any update really did kill their machine, it suggests I have the only invulnerable machine in existence (which is unlikely), or there is some contributing factor that no update can account for. So ask here on this board before actually applying any update to see what is compatible and what is not, or be prepared if you want to be the first to try something new.