What skill level is useful?

Yes. Ax level is entry level. B1 will be at least considered. B2 is preferable. C1 is advanced level. C2 is proficiency.

>>17299665
Thanks for the response. Several online guides say that B1 is about 300 hours of study. Does that sound realistic what you've heard? The reason I am hesitant to believe that number is that the French DELF test says B1 is good enough to travel about in a country that speaks that language. Seems one would be able to achieve that in less than 300 hours.

>>17299796
It depends how deep you immerse yourself in the language. 300 hours are 5 hours Monday to Friday during 3 months. Realistically speaking, it may take more. I took the test for English at C1 level when I was 19 years old, having been learning most of my life. It seemed easy to me, but that's because the language was present during my upbringing. I had an acquaintance who took the B1 English test and failed it, having studied for 3 months, coincidentally. It's all about language immersion.