Hey! I would, of course, be more than happy to share where I downloaded the font used for the poster... if I remembered where I had gotten it.
The font was one I had already downloaded and installed onto my computer but idk if it's one from a resource pack or one I found and downloaded from dafont.com myself. Before I went hunting for a font that matched the one used for the real character posters, I thought it would be a good idea to check through the ones I already had, and the one I settled on matched the best. The best I can do is tell you what the font is called and hope that you can find the right one. In any case, it's called and the font I used is AgencyFB and the font settings I used for the dimensions of Minxie's poster is 325pt with the height at 10 pt, set to metrics with the spacing between letters at -10. I hope this helps, and I'm sorry I couldn't link you to where I originally found the link myself but dafont would be a good place to start looking.
Aa for your Minxie questions, she hasn't actually had anyone to teach her magic. It in her blood, from her mother who is a widely admired and feared sea witch. Unfortunately Minxie was raised by her very human father and doesn't really remember her mother. She realized that she could use magic when she was very young and everything that she can do is a result of trial and error and her teaching herself. Unfortunately, Minxie has a whole lot to learn. Her most reliable magical ability is her talent of turning herself into a cat.
Hope you have a good day too, and I hope this helped. If you have any other questions, I'm happy to answer them!