Also, you can found a GmbH and only pay in 50% of the €25k. My understanding is that you're still personally liable for the rest, but it lowers the hurdle to founding a GmbH at least somewhat.
I also think of reading self-help books (or management books) as giving myself time to engage with the subject. Even if there is no groundbreaking new information, it gives me time to think about the topic. If you couldn't tell yet, I'm a slow reader.
Reading this makes me want to fire up Processing [1] again. I remember spending hours and days with it in my early twenties. The immediacy of writing a few simple commands, hitting "Run" and seeing graphical output is still unsurpassed and created an almost addictive creative feedback loop that I haven't seen anywhere else yet.
digiKam[1] might be for you. I only tried it briefly, but I think it covers most of the requirements out outlined.
I personally landed on Peakto[2], since it has the unique ability to create a unified catalog across multiple CaptureOne sessions, but it's probably overkill for what you need.
Also, you can found a GmbH and only pay in 50% of the €25k. My understanding is that you're still personally liable for the rest, but it lowers the hurdle to founding a GmbH at least somewhat.