Reborn Rich - Questions (spoilers)!

So I just finished Reborn Rich. Really enjoyed the drama and the parallels with a Western show I love, Succession, as well as great acting performances from Song Joong Ki and Lee Sung Min and others.

I realise the ending is generally trashed by fans and differs from the webtoon ending. I didn’t personally think it was a TERRIBLE ending, but thought it was definitely rushed and gave a sense of episodes 2-15 being fun but largely irrelevant drama. But I had some questions on things that confused me nonetheless - if anyone can remember from 3 years ago, grateful for responses!:

1. What happened to Jin Seong Jun (eldest grandson) beyond losing his wife? Was he facing criminal liability for an ordered murder of Yoon Hyun Woo (the “poor version” of the main character) and/or for trying to siphon off the illegal slush fund?

2. A thread from a lot of fans is that episodes 2-15 were irrelevant to the plot - because if you ignore the Jin Do Jun episodes and just watch episodes 1 and 16, Yoon Hyun Woo was attempted murdered by the chaebol, survived the attempted murder, aimed to take revenge and had a recording on his phone to facilitate said revenge. Is the point that, had he not lived as Do Jun, he would not have had the goal of trying to bury Seong Jun and the Jin family for murdering Do Jun, but rather just sought to clear his name (hence the theme of “repentance” for Do Jun)?

3. Do Jun tried to help his future family (ie Hyun Woo’s family) initially in his life as Do Jun eg saving the jobs of the motor company employees his father worked for, buying their restaurant building etc. Why did he suddenly then completely abandon them after his future mother died? Is that just a plothole?

4. Maybe a stupid question, but are Hyun Woo and Do Jun actually meant to look the same (clearly they do to the audience because it’s the same actor) - find it a bit strange that the Miracle CEO, the prosecutor love interest, the entire Jin family etc don’t find it even worth a passing comment that the person who does their dirty work in episode 1 and the person who is trying to bring them down in episode 16 looks identical to Do Jun.