Properly done, latency is not an issue but USB-C hubs are notorious for going to sleep and not waking up with the Mac. Easily fixed by disconnecting and reconnecting but still a PIA.

Do not use a USB external for Time Machine — instead, use a Wifi solution such as one attached to your wireless router via ethernet (can be in another room if you like). That connection should be bulletproof.

True Thunderbolt 3 is also bulletproof but be careful because so-called Thunderbolt compatible is USB with that problem. Thunderbolt is Intel Certified and Thunderbolt compatible is not. Likewise, USB 4 is not TB3 even if rated as fast.

You should have two TB3/4/USB 4 ports and a pair of USB A/USB 3 ports, yes?

Go ahead and connect most peripherals to the USB A ports. Current Fast USB 2 interfaces will not exhibit noticeable latency properly configured.

External storage should be TB3. TB4 is no faster but allows multiple TB3 drives to be attached through a TB4 hub or daisy-chained (TB3 ports cannot do this). You can get certified TB3 drives between 1–8TB depending on your budget. Max R/W speed of a true TB3 drive is about 1/3 the speed of your internal System disk. Don't worry, that's plenty fast enough.

BIAB 2025 Audiophile Mac
24Core/60CoreGPU M2 MacStudioUltra/8TB/192GB Sequoia, M1 MBAir, 2012 MBP
Digital Performer11, LogicPro, Finale27/Dorico/Encore/SmartScorePro64/Notion6 /Overture5