Q1) How do I clone the rpi repo that I visit so much and now can't find?

My Raspberry Pi notes used to be in my "hgpstools" repository, and a few older notes are still there, but I've moved my main and most current Raspberry Pi notes to a separate repository, which is mirrored to GitHub: git clone https://github.com/haukex/raspinotes.git

Q2) Is Plack the solution for my upload question?

Plack is somewhat lower-level, but still relevant, and though I haven't used it myself for this purpose, it is one way to handle file uploads. I would still recommend Mojolicious instead - I don't understand your previous comments about it: "... deployment size and simplicity is relevant. I don't need a lot of software here." Mojo isn't all too big, and only has very few non-core dependencies, so it really isn't that big of a deal, and what you get in exchange is a really good framework.