Will you be fluent in a language when you finish the course on Duolingo?
I'm currently working hard on studying French and slowly introducing myself to German on Duolingo. With French, I base myself off of the Duolingo grammar and vocabulary, but I watch YouTube in French, practice speaking in it, and I text some of my French friends. But once I get to to the end of all the Duolingo lessons in French, will I essentially be fluent, or only have a working knowledge of the language? Thanks! (Sorry if this is in the wrong topic, I didn't know if this also applied to other language courses)
Duolingo can give you a good start with a language. After finishing the lessons, you need to get yourself exposed to other materials. Also, you should spend some time to keep your skill golden. According to what you said, I think you are already on a good path. I have been studying Spanish for six months and I have planned a trip to Mexico and Cuba for 2 weeks. And I think I can improve my Spanish a lot during the trip.
I'll make a claim that some might find controversial, but I that I feel is amply borne out by my personal experience: Duolingo doesn't really do much to help you with speaking. When people say they want to be fluent, I assume it means they want to speak. That's actually the one of the four communicative skills Duolingo is worst at (and in my view it's no close call). However, if you get really good at writing - in particularly formulating quickly sentences in your target language and then writing them down to get them checked, you'll give yourself a very, very significant leg-up in the path to spoken fluency.
Of course, the options for direct conversation are great now, and it's a wonderful option. But if you want to speak well, real-world interlocutors can be somewhat too forgiving. Duolingo trees are great for relentlessly highlighting your errors so you can get past them (it goes without saying that writing practice on Duolingo is mostly on reverse / laddered trees).
The short answer is no, but it sounds like you are already aware of the fact that you have to expose yourself in different ways and with different methods to advance in a language. Keep that up!
It's great by the way that you have French friends to text with, but you might consider stepping up your French game by having skype conversations with them. This will definitely improve your active understanding of the language.
Unfortunately not, but I do believe that doing ALL courses that involve that language (including reverse courses and laddering courses from other language) and keeping them gold for the most part, will give you a solid path to fluency. In your case, that means doing the reverse courses (Englisch für Deutschsprachige and Anglais pour les personnes parlant français), as well as Französisch für Deutschsprachige and Allemand pour les personnes parlant français .
After three years here with the streak that you see, I believe I am fluent (or pretty close to fluent) in Spanish. Also, I am very close to fluency in Italian. But, I must point out that I did know some Spanish even before joining Duolingo, bits and pieces that I picked up in my childhood from the telenovelas that my grandmothers used to watch.
No, but it's a good first step. You need to find a way to include more listening (some of the new labs in Duolingo will help), read as much as you can in your target language, and try to find a conversation group of some sort to be really fluent (in the sense that you can understand conversation and join in with a reasonable amount of ease.) It takes practice, as speaking and listening are different skills than reading and translating.