I am about to receive a new (used) touch screen laptop. My web searches reveal that KDE Plasma is one of the better desktops for a touchscreen. I have a pretty long history using PCLinuxOS with the Mate desktop (non-touchscreen). So, I will be making a fresh install of PCLinuxOS and choose the KDE Plasma desktop for it this time. I have never used KDE but, I have found the Users Wiki and will be making use of that. Otherwise, I am wondering if anyone has any advice on installation, startup, and learning. Thanks

This entirely depends on your use-case: what do you want to do with it?
I don't know PCLinux at all, but if you want something very Plasma specific there are probably better distributions out there, KDE Neon and Kubuntu come to mind, as well as Opensuse or Manjaro

I don't know PCLinux, a long time ago I heard about it well, but as I wrote I don't know it. I have been using openSUSE for years and I am happy with it, so I cannot tell you how PCLinux ships Plasma, if it distributes a vanilla version you will not have problems, otherwise you can ask in their forum. Plasma is a fantastic DE, it allows you to shape your customized DE. I personally make few changes, because I find it excellent as it is. A greeting.

I've used PCLinuxOS as my primary desktop at home for years. KDE/Plasma is the primary desktop provided on it (other desktops are available, but are largely secondary), which it keeps fairly up-to-date with a stable rolling-release model (not bleeding-edge like Arch, new packages are released after some testing to make sure they don't break anything).
The main downside (currently) is no package-kit support, meaning no Discover (installation and updates are still all done entirely in synaptic).

Try it out and see how it goes. You should find Plasma to be easy to use and highly configurable to your liking.

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very interesting.