hello again
got 2 questions

1. why does linux keep apps running even if you close them ?
doesn't that simply occupy memory for no reason (at least on old crappy machines)

2. old hardware drivers, i dont know how linux distro's handle drivers,
in windows, it was always some generic that came with instalation
but usually you have to go to HW manufacturer web site and find
your own chipset, sound, graphic, LAN

how does linux, as it every 6 months gets new and new versions
how does it handle old hardware drivers ?

1. That very much depends on the app. Monitoring applications will not monitor if they're not running. And some applications are designed to keep running after the user logs out. So which specific apps are you asking about?

2. Much of the interfacing code is written into the kernel already. There is no need to get drivers for, say, an old ATi or nVidia video card or Tulip-based Ethernet card because they are already in the kernel. At one point the Linux kernel supported more hardware as-delivered than Windows did, but that is a slightly invidious comparison because, as you say, "[U]sually you have to go to HW manufacturer web site and find your own chipset, sound, graphic, LAN". It's already there with Linux.

Which distro are you using? There are some distros that ship GNOME but don't ship a system tray extension. Which means that apps that should go to the system tray just disappear because they have nowhere to go.

The solution is to install a system tray extension. It's usually in the distro's "app store", and it usually has "appindicator" somewhere in its name.

Hardware drivers ship with the distribution and get upgraded with updates to the distribution. That's really all you need to know as an end user.

Except for graphics, all Linux hardware drivers are in the kernel. Generally speaking, old hardware is supported for quite a long time. For very new hardware, you may sometimes need to install a kernel more recent than the one in your distro.

For graphics, you typically have two co-operating drivers. One is part of the Xorg server, and the other is a kernel module to deal with things like mode switching.

Scanner and printer drivers aren't in the kernel.

Touché! What I should have said is that the kernel has all the drivers for hardware that is controlled by your cpu. Scanners and printers have their own internal processor.

Most of the newer distros I am familiar with have a 'linux-firmware' package (or equivalent) that contains the updated firmware for different devices and loads the parts needed at boot. That package gets updated when necessary so the user usually never needs to worry about it.

Drivers and firmware are different. Drivers connect the kernel to the device firmware interface. Firmware handles the device hardware directly, and used to be exclusively in an eeprom on the device but more recently on many devices can be loaded at startup time into device memory by the OS.