Some questions about mundane medieval books

Salvete, Sodales!

The magi in my saga plan to extend their library, and they are not only interested in mystical stuff but would also like to have texts about various mundane subjects. I know that there were such texts in antique Greece And Rome, e.g. Xenophon's texts about horsemanship or hunting, but were there available Latin versions of them in 13th century western Europe? If yes, how would you evaluate them (tractati/summae?, level/quality?)?

Then I wonder whether there were any books around in order to learn foreign languages - primarily Greek and Arabic - which were written for people who were not already proficient in these languages?

If anybody has knowledge here, please answer.

Alexios ex Miscellanea

I believe Arts & Acadame has some rules for how one improves their Academic languages. Basically, the notion is that you get taught up through the point where you can read, and once you're able to read a book on an academic subject, you can always take half of the quality of the book you're reading and apply it to the language it's written in, and the other half in the subject it's on.