Conflict with Super Cache or Quick Cache?

Hi,

Yes, they conflict and there’s no advantage using those together.
However, you can add an object cache plugin, if you wish, beside wp-ffpc.

OK, thanks.

What about autoptimize, which concatenates and minimizes js and css?

I have not tested the plugin against all the other optimization plugins, please feel free to do so and share the results.

Confirmed. Works nicely with autoptimize.