I have many nerdy friends who have been Linux users for ages. But most of them don’t know such a thing as Openwrt exists or have never bothered to give it a try. It’s a very fun piece of software to play with and can be extremely useful for routing traffic. Wondering why it isn’t more popular/widely used.
You really want to either update to a supported release or stop using it entirely. It is very insecure to run network equipment with known security issues
It is still much more secure than to stop using it and let your other devices go naked.
Not necessarily. I would at least keep your eye out for something newer.