My grandmother was born in France, and moved to the US where she had my father. My father, a US citizen, is applying for French citizenship through descent as his mother did not renounce her French citizenship until after my father was born. He seems to have all of the paperwork in oder, so I'm guessing this will eventually be granted based on what I have read. When/if my father gains French citizenship through descent, does that mean I, too, as his daughter can also apply? I can't figure this out and have seen conflicting information. Lastly, I can't figure out if you need to be fluent in French in order to obtain French citizenship through descent.
Citizenship by descent isn't something that one "applies for." Rather, it is something that one acquires at birth through the automatic operation of law. Your father is applying to have his French citizenship recognized by the French government. If the French government does recognize it, it will mean that the government recognizes that he has been a French citizen since he was born. That in turn will mean that you are the child of a French citizen, and therefore also a French citizen.
You do not need to have any French skills to have French citizenship by descent. French language skills are required for naturalization, as evidence of integration into French society, but that does not apply in your case.
@phoog correctly explained that citizenship by birth is not something you gain but something you either already have or don't have. If you do have it, French language skills are irrelevant and you cannot lose it.
That said, there are complex rules that effectively means that French citizenship by birth can lapse after two generations if you don't use it (see e.g. Will it be possible to get French citizenship?). I believe that your father being granted a passport or certificate of citizenship would effectively reset the clock and allow you to make use of your French citizenship as well but I am not entirely sure of the details (and it would also depends on his and your age).
Unfortunately, if your grandmother lived most of her life in the US, your father is over 50 and it's the first time he is applying for a French passport, he could have trouble getting his citizenship recognized now, even if he was definitely born a French citizen and all the paperwork is in order.