If I complete all the tests here, on a scale of A1 to C2, what do you think my level will be?
A2/B1 if you work hard on the grammar. It won't be across the board though as your speaking ability will be poor if you just use duolingo. Perhaps look in your area for French tutors or check out italki.com for speaking practice. I speak French to a C2 level but that's from school and the university, and living in France. However, I started teaching myself Italian through duolingo, alongside other resources, and also using italki once a week to have a speaking lesson and I managed to get to B2 within about 6-7 months. My knowledge of French though obviously helped me to progress more quickly than a complete beginner.