Once installation is completed, and Kleopatra launches I recommend you create a private key.
Why would you recommend me to create a private key? Note that this can be very confusing for a newbie. Do I need a private key for the certification of Thomas' identity or is it just
recommended after all?
You don't need a private key or to certify anything to verify stuff, the certify process is only to remove the bogus "This key is not trusted" warnings. Some suites may not even display it at all (GPGtools does insist on making a keypair though, I wonder if you can skip that part).