How do I access the darknet as I'm curious to know what goes on there.
Download the Tor browser. And if you're curious on what's going on there, there's a lot of scams, and that's pretty much it.
That ecosystem found BTC very useful in the past, is it still actively using it as a form of value transfer?
Of course.
Or is bitcoin totally useless in terms of covering one's tracks?
You can use Coinjoin programs such as Samourai or Wasabi, or you can also use mixers like ChipMixer if you value privacy(which you should).
What's the process of linking up to know aht's going onj in there to gather news?
All that you need to know with bitcoin and the darknet markets is that the people who are receiving bitcoin there are drug dealers and scammers.