For the rest of the author's life + 50 years after his death.

Two weeks.

Civil and criminal.

In most cases no.

Not compulsory, but recommendable. No consequences.

Not compulsory, but recommendable. No consequences.

No.

Copyright protection for any literary or artistic work is automatic and does not depend on additional registration formalities.

The text of the online published personal study may be protected under copyright provided that it includes a sufficient amount of original creation.

If the unauthorized use of your copyrighted work does not fall within the scope of the limitations and exceptions to copyright, and you feel that there is an infringement of your right, it is possible to raise legal action against the infringing party requesting monetary compensation as well as preventing the continuation of the unauthorized use.
However, before choosing the legal action option, you may first consider directly contacting the infringing party to ask for compensation and that they cease the unauthorized use, or use an alternative dispute resolution mechanism (i.e. mediation, arbitration, etc.) to avoid incurring high costs for legal action.

Once you become aware that a work you have already used is protected by copyright, the safest option would be to directly contact the owner of the right in order to explain the situation, obtain a formal approval on continuing your use of his work, and agree on the terms of the use.
If possible, you may also make an amendment to add the necessary citation in the place where you have used the copyrighted work so as not to be considered infringing on the right of the owner.

It is possible to use pictures or quotes found on the Internet, and for which the time of copyright protection has not yet expired, in someone’s marketing materials only upon obtaining permission from their owner/author.

An unpublished work set in a tangible medium of expression enjoys copyright protection similar to a published work, provided that it meets the requirement of originality.