To put it simply, "targeting" the EU market means that a product is openly made available for purchase by residents of any single country in the EU by someone outside the EU.
There are three main types of market entities, or "economic operators," that engage in the production, distribution, and sale of products. The lines of each and definitions may differ from your understanding, but these were set up to at least have decent definitions for this regulation.
This depends on the situation, but, in general, this item will need to follow the GPSR in order for you to send it to the EU.
All vintage/second-hand items that haven't been listed for sale to the EU prior to Dec. 13th, 2024 are subject to the General Product Safety Regulation.
Yes. Whether or not you have a registered business doesn't matter. In fact, you can have a large business but be exempt from the GPSR, but that's too complicated for this video.
Yes, you almost certainly do. As the GPSR is written, it's more so the products that are regulated, not the individual. What matters most is whether or not the product was "targeted" to residents of the EU.