Yes, they do.

I think it's mostly (depending in the specific Version/OS) about 10 minutes default. For example, the Google Clock app lets you change the "silce after" option, with the default being 10 minutes.

Edit: I've tried to look for your specific alarm app but couldn't find anything online (and I don't want to download it just for testing), but maybe you could just download it wherever you are right now and search of there is a default option or test it?

Yes

A private YouTube client

I host https://proxigram.kyun.li and it is currently down, will work again soon :)

EDIT: Instance is working again

Lifehack is just to use . and , to skip forward/backwards for 0.1 seconds in a video

It depends on the video chat service you want to install.

https://catbox.moe/

There is no reset button since it is an unmanaged switch, so it's just plug and play. I'm sure it gets proper amount of power. The support now just told me that the best would be to just get a replacement.

Tried with with different cables again and tried to connect a notebook and a raspberry pi. I've also tried every single port, but nothing shows up on the devices and no LEDs flash/blink. :(