C4 Issues

I hate pan gaskets and always use Black RTV to seal them... You can probably get a new seal kit that would include the rear extension and servo gaskets, for only a few bucks or the needed gaskets individually from a transmission parts store.

You were told the correct thing about installing dry. Sounds like you torqued them down too much. Next time, don't install those gaskets until you're ready to put the tranny to use, they need to heat up and have tranny fluid seal up the internal edges.

You want to try VERY hard to hold the servo piston in place while you get the new gasket in place... if you here a clunk, you'll have to pull the valvebody out to replace the end of the band adjuster. But the valvebody R&R is pretty simple, as you know. Just be sure to replace the pan last..just in case.

I wouldn't use anything on the paper gaskets, but you could use some aviation grade gasket sealer, if you wanted.

I doubt that getting the tranny hot at this point would help seal up the leaks, since you've torqued them down twice... its good that the gasket kits are cheap.

Good luck with the leaks...C4s love to leave a bit of their "blood" everywhere they go.