Can my employer own my personal work made outside of work hours

I have just been offered an interview for my first Graphic Design job outside of commissions and college, but I had a quick question about ownership rights for artwork. In my spare time, I create artwork and designs not only for personal use, but for one-off commissions as well. Does my employer own the rights to these when they are made while employed? Here are some scenarios for example

At what point does one decide a font is in the public domain?

I’ve tried to find who created the font Orion Esperanto Normala (which is quite similar to Arial), but none of the distributions I’ve found have either stated the author’s name or included any kind of licence. So it sounds as though it’s in the public domain and can therefore be used and modified at will by anybody for either private or commercial purposes. But is that accurate?

Is sketching or drawing someone else’s photograph a copyright violation?

If someone were to sketch or draw (digital or otherwise) an existing photograph by someone else of say, the Pyramids of Giza (by “photograph”, I’m referring to images taken with a camera and not other sketches and drawings), would it be a copyright violation if one were to, for example use the sketch or drawing as a background in a poster or incorporate it along with an existing creative that one might be working on?

When to tell long-term client I’m retiring within the next year

For fiteen years I’ve been designing a quarterly forty-page publication (print & online) and numerous other smaller projects for a small city. Now I’m planning to retire in the next six to twelve months. I haven’t yet told my client this. How far in advance should I do so? And when/how do I approach the subject of selling them the native InDesign files?