I always play exhange variation as white, and I think c5 is a mistake to play for black in your situation. Typically Bd6 and Bd3 are stronger bishops. In response to Nc3 like white played, as black I would typically just play Nf6 inviting Bg5 allowing the option now of Nbd7 or even c6 which gives me a very strong set up as black.
Playing Exchange like Advance in French
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like the people before me have said moves from a different variation doesn't always apply to the variation you are playing so don't do it!
besides that the exchange french can be just a boring symmetrical dry drawish position and personally i reccomend a setup with Bd6, Ne7, Bf5, Nc6, Qd7, o-o-o the point of Ne7 is to support a bishop on f5 because white tends to put their bishop on d3 which attacks the f5 square and also the knight on d7 allows you to play f6 defending the e5 square from a knight trying to get there and if white trys to pin down the knight f6 is played with tempo and you follow up with g5 and h5 if your opponent castles kingside for example:
4.Nc3 is all right. White wants to move all the pieces off the back rank, castle long, and pawnstorm the kingside, just like Black does if White commits to a setup with Nf3. 4...Bb4 is the most common, statistically, because this position is more commonly reached via 1.e4 e6 2.d4 d5 3.Nc3 Bb4 4.exd5 (the Winawer Exchange, in the time of Capablanca this was considered the most principled approach for White) exd5.
On 5.Bd3 (instead of this guy's Bd2) Ne7 6.Qh5, we have the Canal attack, which can be quite exciting if White is willing to sacrifice the exchange like in this game:
Things have been falling together for me a little bit of late with the French. That's an understatement actually. That's all I'll play in response to E4 from here on out. Might as well pass along whatever meager knowledge I've gleaned.
One thing I'm doing is playing all the same typical moves associated with the advance variation with the exchange as well. Have played a bunch of games just like this. For me the French never turns out closed or defensive, even in the advance.