"Are foxes friendly and sly animals?"
Translation:A rókák barátságos és ravasz állatok?
The "-e" suffix here is also OK here, and sounds better to me. "A rókák barátságos és ravasz állatok-e?"
The '-e' suffix means something like 'whether/if' so you don't need here. But it can be a dialectal thing: my relatives around the town Szolnok sometimes speak like this.
I didn't say you need it per se. But you can use it. Can you give me a "whether/if" situation you're thinking of (in a question)? Or do you just mean sentences like "I don't know whether this makes sense" = "nem tudom, hogy van-e ennek értelme"? I would call that opinion nonstandard.
My opinion is that in a question the 'e' little world is not just unnecessery but even sounds wrong. I was born and raised in Budapest and I have never heard people here saying 'e' in a simple question (maybe in a retorical question it is not wrong but very few people would use it even that way and the above sentence is not a rethorical one). So in the capital city it is not used.
Making a little research, the usage of 'e' is ambigious (even that where you should put it) http://www.nyest.hu/hirek/az-eltevedt-kerdoszo-nyomaban
Random people commenting, 2 of them call 'e' 'countryside like' and that it is only in dialect (the 4th and 10th)
https://www.google.se/webhp?client=firefox-b%3De+haszn%C3%A1lata%3D1%3DX%3D0ahUKEwiy4KTfxrjQAhVIDCwKHYoNCLEQvwUIGSgA#q=hogyan+haszn%C3%A1ljuk+az+%22e%22+bet%C5%B1t%3F+gyakorikerdesek.hu First result. Sorry I could not link it directly because of Duolingo
And that's what I know about it: if you would say 'A rókák barátságos és ravasz állatok-e?' people would look at you in Budapest as 'oh that guy is from the countryside' or 'oh that guy is uneducated'. It is maybe unfair opposition of the city and outside the city but very common: some of my classmates in primary school made fun of some of them's grandmother who used the 'e' word in a simple question (kids are evil sometimes). And the 4th comment in the above link also made fun of countryside people in a very rude way by the way.
And yes, this is the appropriate usage of 'e' in my opinion:
'I don't know whether this makes sense' = 'nem tudom, hogy van-e ennek értelme'
'I always wanted to know if foxes are friendly and sly animals' 'mindig is tudni akartam, hogy vajon a rókák ravasz és barátságos állatok-e'
So all in all: the 'e' word is very tricky in Hungarian, even native Hungarian can't agree on it. In Budapest it is used only in reported speech and never in simple questions. Outside Budapest it can be used in simple questions as well (but I am not sure where exactly, I'd say that only in little towns and villages, I would doubt that it is widely used in relatively bigger towns like Debrecen, Szeged, Miskolc, Pécs or Győr).