Yes, good advice. Unfortunately my old EDA no longer works on Windows without serious problems (CircuitMaker 2000). I had a board hanging that could not be manufactured so it was the trigger to go with KiCAD (I donated $80 BTW ).
The board went off this morning - hopefully the PCB house will not find any issues now.
Yes, of course. In … / Preferences / Manage Symbol Libraries there are two tab pages. By clicking on the plus icon at the bottom you can add a library. Global libraries are visible in all projects, and Project specific libraries are Project specific libraries. Library management has been described in detail a lot of times and places. Including on this forum.
If you want to use global libraries, then put them in some sensible place. You can also work with environment variables in paths. For example, I have made a ${KICAD_DATASHEET_DIR} and use it in schematic symbols to link to locally stored datasheets.