If you go for the Livebox Zen package via ADSL (max connect speed 24Mbps) then it is 33.99€ per month with 3€ on top of that for the Livebox. If you only want internet then you can save the 3€ and supply your own modem (bit of technical savvy needed). If you want the phone you will have to stump up the 3€ as your phone needs to plug into the Livebox. If you want the TV on top of Internet plus phone it isn't anything extra per month but there is a 50€ or so "deposit" for the TV box.
Calls are via VOIP (hence having to plug the phone into the Livebox) and you do not pay a separate fee for the line. If you have an existing French "geographic" number you should be able to keep it.
If you live in an area where VDSL is available and you want VDSL (connection speed up to 80Mbps) then you have to take the Livebox - at least that is what I was told when I ordered my VDSL service to discover that I only had ADSL. I took the TV package but, to be honest, I still haven't set the ***** thing up.
Like all things telecoms related getting your head around prices and what the service involves can be a headache.