French - Use of hyphens, salle de bain and comparatives in lesson 5.4

Hi,
I am coming across certain things that I find discrepant, or at least I don't really get.
Please help me understand
1. Hyphens- especially in writing large numbers. Sometimes i see them used, sometimes not. Are there any rules?
2. Is it "Salle de bain", "salle de bains" or "salle-de-bain"? I have seen so far the three variations.
3. In lesson 5.4, there is use of comparatives and it is as "Moins de" and "plus de", instead of "moins que" and "plus que", why is that?

Thanks
 

Bonjour BertaV,

Hyphens are a bit of a pain for French speakers as well. They are a relatively recent introduction, with spelling reform introducing a swathe of new hyphens in the early 90s. However, they haven't been well enforced and French dictionaries and other reference guides have been, up until now, fairly relaxed in their inclusion of them or otherwise. 

So to answer your questions:
1) Hyphens are used in numbers and the spelling reform states that a hyphen must be placed between all words of a compound number, i.e. vingt-et-un, trois-cents. However, you will even get French people using hyphens at their own discretion.
2) Hyphens are often used in compound words but not for salle de bain (or salle de bains, either option is fine).
3) In the former, 'de' will always be followed by a noun, thus it will be a comparison of a noun, while 'que' will be followed by pronoun or verb so it is comparing actions.

I hope this is clear enough. Please let me know if not.

  -   Marie-Claire