Re: Examining Catalina 22
That hull is solid glass.
If it's had water in it a while, I'd be looking at the condition of the bulkheads.
There's plenty to be wary of, even in a 22 footer. While the hull is solid, the deck is not, so you want to know if there's any water in the balsa core. I would not rule out a professional survey on the boat, no matter how low the price. That boat could bite you good.
One of the regulars on this site has a checklist for checking out a boat...think it's SailingDog.
Also, I'm recommending that you limit your posts to one topic per post. Stick with your questions about the determining the soundness of the boat in one posting. Questions about safety gear, and suitability of the boat as a learning platform are best left to separate posts. Otherwise you risk getting fewer replies because responders don't want to answer ALL your questions.
I'm not sure how to answer your question no. 6. Doesn't sound like typical "tabbing", but hard to say without a picture. Could be the hull deformed from the weight of the water in it.
You came to the right place, though. If you don't get answers on this forum, there is no answer.