Yeah, solar plexus is fine. And I also think targeting the neck is underrated. If I was being detailed, I'd say punch (or elbow or backhand, but not kick) something at a reasonable punching height, which is physiologically (not pressure point nonsense) necessary to keep fighting (usually responsible for bloodflow or breathing). But when we start talking about controlling joints or disabling limbs or whatever complicated thing... eh.

I have met multiple people who study "kung fu" at a local dojo and ended up very strong, with very solid stances reminiscent of karate, and reasonable understanding of how to fight. "Kung fu" doesn't mean anything though. Apparently some people who know things still market their training as kung fu.

I studied TKD more than any other martial art. It's okay for self defense. You still learn spacing, footwork, and how to strike with follow-through, which are applicable anywhere. You learn how to roundhouse someone at head height, which I don't think is a great plan, but it will still end a fight immediately if done successfully. It's a little too reliant on having a decent amount of space around you (which has a lot of overlap with situations where you could just run away instead). A lot of its kicks and stances are vulnerable to someone simply jumping towards you at the wrong time.