léa 1999 (parfois anise)

[zealous dome]

Please be patient

Our volunteers look into many questions every day; sometimes it takes them a little while to answer.

Pro tip: you can rename the thread title with `.tr <thread name>`

Make it descriptive, including relevant context, but also to the point. This way you improve your chances of getting a more relevant and specific answer.

[tall cloak]

Very common. You can definitely use « est-ce que », even intonation, in formal contexts.
If you're ringing up a hotel, you can go, « Quelle sorte de chambres disponible est-ce que vous avez ? »
You can equally call an office and ask, « À quelle heure est-ce que la réunion aura lieu ? »
As for intonation, it depends on distance. If your client is someone you've known for long enough that a friendly rapport has built up, you can go, « La réunion va commencer quand ? Vous le savez ? »

Intonation in regards to the hotel thing is the part that I'm unsure of. I'm sure you can use intonation there (vous avez combien de chambres disponsibles ?) but I'm just unsure as to the context in which it appears. Spoken French does give you more leeway with using est-ce que and intonation but that doesn't mean that inversion is never used.

[round thorn]

I agree with what berie has said, generally, but inversion is by far the least common option of the three, particularly for yes-no questions in France. From what I understand inversion is still frequently used for yes-no questions in Quebec and isn't viewed as so formal as in France