In context it would mean: they are completely unconvinced stock returns will be better in future than it was in the past (at the time they were writing). This makes sense and I believe was borne out in fact, average annual returns on US stocks have been falling for several decades - hope that helps.

it's a useful phrase to say "an absolute no" - like somebody immediately decided no, and they won't change their mind.

"by" would need it to be an action - e.g. "birthed by a virgin" would work, alternatively "by" can indicate location, meaning "born by a virgin" would mean someone was born... next to a virgin(?). Would be strange to say either of those though - I've never heard anyone say anything other than the two you mentioned in your question.

There's not a significant difference, but if I could classify them by how formal they are I'd say: pay - the most casual/least formal - examples: "I got paid today" , "I need higher pay to buy a house" - it's the way you'd talk among friends, not so much when talking with your boss. wage - more formal - examples: "You'll get your wages monthly" , "Accountants normally have a higher wage than shop assistants" . In my mind it's a more 'working class' term, I wouldn't expect a senior executive to talk about their "wage", only low or middle income workers. salary - a bit more professional than wage, when negotiating a pay rise at work, for example. Examples - "An annual salary of $30,000 won't get you far these days" , "He changed companies to secure a higher salary". I would expect more senior staff to tend to talk about 'salary' rather than 'wages', although they are synonyms and interchangeable, they just have slightly different connotations. Hope that helps, let me know if you're not clear!

Yes

It would be more typical to say "I wish I could turn back time", if you still regret that presently. If you mean, you regretted before but now you don't: "I wished I could have turned back time" would be clearer than what you have written.

In this example, I think leaving out "the" sounds more natural. Be careful, as sometimes "the" is not appropriate, for example you should say "most of the time I go fishing alone", not "the most of the time I go fishing alone" - I think it's quite rare for sentences to have two 'thes' in it