Unless you're using Linux on a virtual machine, installing the open-source OS is usually done via a USB drive. Because of this, you can burn an ISO to a USB drive, reboot the system, boot into the USB ...
Whatever the case, a portable Linux installation on a flash drive can be used in place of a normal storage drive in your PC.
However, if you put a portable Linux installation on a flash drive, you can carry your own operating system with you wherever ...
RAM is a crucial component for a smooth PC experience. Linux doesn't require as much RAM as Windows. More is always better. I'm not going to start this with a "back in the day" because it's too easy ...