Which delimiter should I pick?
Comma if the file is going into a script or a database import, since that is what almost every parser defaults to. Semicolon if you are opening it in Excel on a machine set to a locale that uses a comma for decimals, because Excel will otherwise split on the decimal points and produce a mess. Tab is the safest option when the data itself might contain commas.
How are quotes and commas inside values handled?
A value is wrapped in double quotes if it contains a comma, a double quote, or a newline, and any embedded double quotes are doubled, which is the RFC 4180 convention that Excel and most parsers understand. None of the built-in types actually produce those characters, so the output is normally unquoted.
Can I make one of the columns unique?
No. Every value is drawn independently from the pool for that type, so duplicates are expected as the row count grows: with only 20 first names and 16 last names in the bank, a hundred rows will repeat. Generate, then de-duplicate, or use the UUID type for a column that needs to be practically unique.
Are the numbers formatted for a particular locale?
No. Floats use a dot as the decimal separator and there are no thousands separators, which is what a parser wants. If you are handing the file to a spreadsheet in a comma-decimal locale, use the semicolon delimiter, and be aware you may still have to tell the spreadsheet that the dot is the decimal mark.
Is any of this data real?
No, and that is the point. The names are drawn from a small list of computing pioneers and generic first names, the emails are assembled from those names and a fake domain, and none of it corresponds to a real person. That makes it safe to paste into a shared test fixture, unlike a sample of production data.