Identify connected PC per Arduino Question:
Is there a way to collect any data (e.g. MAC addresses, installed devices, driver versions, etc.) from a PC by simply connecting an Arduino via USB to it, so that this PC can be clearly identified? 

Background:
Basically, I`m using an Arduino to send some text to a computer by emulating a keyboard, but I don´t want the text to be sent to any computer I connect the Arduino with. That is why I want the PC to be identified first.

To be clear: this should be done without having to install programs on the PC in the first place.
No you cannot. Arduino communicates to pc via UART so there must be a host which can send or receive the data. You have to install software on the host computer which can send and receive data to the com port to which arduino is connected to.