I agree with Wes but "lukewarm actions" sounds a bit unusual to me in this usage. I would probably say something like "half measures" to convey this meaning instead. For example: Half measures do not work. We must take full action instead. We don't take any half measures. Usually when we use the word lukewarm in a figurative sense it would be to convey an unenthusiastic response to something. For example: The latest film was met with a lukewarm response.

Yes, that is a common phrase. You could also say "fall into poverty" as in: He fell into poverty after losing his job. He was reduced to poverty after losing his job.

To rise to riches means to become wealthy.

People are afraid that there will be a shortage of toilet paper and are trying to stock up. In reality, such fears are completely unfounded as there are no issues with the supply chain here. There's really no reason other than panic.

Here's how I would interpret these sentences: 1. The first time that I saw him was on YouTube (I had not seen him anywhere before) 2. There would be some sort of follow-up to this statement. E.g. I later met him in person. 3. Not correct 4,5. These are a bit ambiguous to me. It could mean the same as 1, but could also mean that it was the first time that I saw him while on YouTube (implying that I had seen him before elsewhere)

Did they give you a reason why they can't provide a refund? If you paid using a credit card that provides trip cancellation insurance coverage, then that is another possibility.

Do you mean "cousins"? A cousin is a child of an aunt or uncle.