The 2011 ISO does not work because of the kernel issue?
If it does not boot from USB then the files relating to it can be deleted.
You can try running the LiveUSB creater utility before deleting the 2011 files ..... it will give an error if there is not sufficient space.
If that happens then you can delete the files and run it again.
Overall meme I believe you are hitting memory problems .... and the only way out of that - that I am aware of - is to increase the fitted memory.
So my opinion is that you need to either increase the memory, or revert to a much 'lighter' desktop environment ..... LXDE, Xfce or Openbox.
You may find that with one of those installed to your existing KDE installation, and selecting the lighter DE at log in, would allow you to use the PC without the 'freezes' you are experiencing.
All your apps would still be available, but you would need to be aware of the memory limitations and not run many at the same time, or have many web pages open together.
Essentially you are between a rock and a hard place ..... either the hardware changes or you change your DE, or accept the limitations and problems you are experiencing.
Not easy choices, any of them, unfortunately