[wayner]

I am no lawyer but I own some copyrights.

Generally, any works are the property of the author.
Laws vary by country.

Work for hire in the US is owned by the employer by default unless it is retained by the author contractually.
In Canada it is owned by the author unless assigned to another contractually.

Any works of mine, regardless of who is in posession of those works, are mine unless I have assigned copyright to another person or entity ( in other words in the scenario above, if the person is still living, you should ask their permission before publishing)

There are allowances for fair use (excerpts) but again, asking permission is advised, especially if you plan to make money on them, otherwise the owner/author can sue you for the money (don't sell my stuff).
Laws in various countries differ.

A good example for the questions above are the books on your bookshelf. You own the book. You are in possession of the book, but you do not own the copyright.

Posts in a public forum are already in the public domain and are assumed publicly available unless protected.
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