Yeah, the new season will be hard to understand without at least reading the plot of the original series! So the original series was made for regular TV, so even if violence was implied, it wasn't so explicitly shown. It was also a bit cheesy. David Lynch was most involved in season 1, and it was like Lynch's take on a soap opera, imho at least - then he wasn't very involved with season 2, and it was pretty awful - just ridiculous. Firewalk with Me, being a movie, I guess, was far more intense than it could be on TV, more explicitly shown violence and everything else (you saw it) - I only mention that, because I actually do not like viewing material like that - the storyline is intriguing though. Firewalk with me shows what led up to the Twin Peaks original series, and of course, now The return is 25 years after that original series ended. So the main plot line does come from the original series, there were many mysterious things left unexplained. I think I would have to at least read a summary of the Original Series to be able to understand the Return.
What is your favorite David Lynch movie? I've only seen a few - but my favorite was "Lost Highway".