Oh my goodness, I'm so vanilla with my setup on this thread its laughable.
I went from a '13 iMac to a 2022 M2 Mini with a Satechi USB HUB. Both Mini and HUB were perfectly capable/matched. I sold the M2 Mini & Hub less than a year on whilst values were still reasonable and replaced with the current M4 Mini due to the spec upgrade. My current is the base model, 256GB/16GB RAM
1) I am also a light surfer/emailer. I use Music/TV and Photos the most. The Media element is all stored on external SSD's and basically feed my Apple TV. Photos are also stored externally as I take a lot and edit a lot. The Mac is more than capable of this task even with the Photos being stored externally. I occasionally do some design work on Affinity Designer & Photos: the Mac tackles both of those with ease.
2) In relation to hubs, I'd have no hesitation in buying another Satechi, but I don't quite have the need for it at the moment. I would have no hesitation in recommending in the future.
3) Keyboard-yet more vanilla: I use the an Apple keyboard with touch ID (wireless), and matching Magic Mouse. I picked up both in a bundle, new, on eBay. No issues for me using those.
4) Sound-Mac Mini speakers are fine for notifications and the odd tutorial video, but if listening to something for longer, I either use my AirPods if other people are about, or I use my (now very old!) Bose Soundlink speaker. Works a treat.
5) Not sure due to your location, but here in the UK, the Satechi occasionally appears on Amazon with about £25 off. In a few years time I may consider this route and popping an SSD in there: I've always run my Macs lean with everything stored externally, and have no issue adding storage to the Mac this way Equally, the Sabrent enclosures and Crucial SSD's are cheap and run really well with my Mini, so I'd happily add another in the furture if a Hub wasn't necessary. In terms of longevity, if I could have afforded the 512GB storage I would, but couldn't. Happy with the RAM combined with the M4, it has been super fast.