lol, aren't you important.
If my tone came off wrong, take it easy. It's been a rough time around here helping people.
As are all the helpers on this site, I am a volunteer who likes WordPress. Which, by the way, thank you for judging me... I appreciate how helpful you've been to the community here.
I was honestly trying to answer any questions you asked. And I feel I did.
You seem to have asked 3 questions, all of which I answered.
#1 Where is the debug feature: The debug feature is a plugin, which was linked previously.
#2 If a site skips a few updates, could it cause problems. YES it can leave you vulnerable to hacks. Nearly all WP updates contain security updates. It is always recommended to update immediately. Nobody here will ever say differently.
#3 When and why updates needed? THey are released as needed for security, and semi-regularly (on a loose schedule) for feature enhancements. And should be updated immediately. See previous answer.
If you are worried about plugins not being compatible, set up a dev install somewhere. Its what most people do. At some point, you will lose a plugin. They aren't all going to be supported forever. You have to find subs sometimes
There, I have tried to read between the lines and answer the questions you asked, plus what you didn't really ask but seem to have expected someone to figure out you meant.
@GusTavox, please start a new thread. It is considered rude to hijack someone else's thread, plus it causes confusion