French language Q&A Forum

So when do you use "Qu'est-ce que c'est"  (What is the Sacré Cœur in Paris?) and when "Qu'est-ce que c'est que" (What is the Sacré Cœur in Paris?)

Qu'est-ce que c'est ?
What is it?

Qu'est-ce que c'est, le Sacré Cœur à Paris ?
What is the Sacré Cœur in Paris?

Qu'est-ce que c'est que le Sacré Coeur à Paris ?
What is the Sacré Coeur in Paris?

Is the the use of future simple here common in daily French? My understanding is that the use of the reflexive implies the action of sitting down, rather than the idea of being seated somewhere. Would a more natural way of expressing this be:

Dans l'Eurostar, vous serez assis près de la porte.

I realize they have different meanings, but it seems a bit odd to refer to the action of sitting down in this context.

I’ve only ever seen the adjective tricoloured ie. similar to French, in English