i know GM made at least one CVT with a torque converter(think it was a joint venture with toyota?).... i want to say it was continuously locked above ~10MPH.
a torque converter can multiply torque... it's kind of strange to think about though. in any case, when it's multiplying torque, it's also slipping to the point of stall, which is not what anybody interested in efficiency would be interested in. see:
Torque converter - Wikipedia, the free encyclopedia
ATF in the torque converter moves around quite a bit. if it didn't, whenever the torque converter clutch locked, small amounts of clutch material would shed off every time. if it never got pushed out and filtered, it would build up and cause issues.
too many gears? depends on who you ask. if you like constant shifting to keep at BSFC peak, you can never have enough gears. anything above 6 feels excessive to me, even then, calibration dependant. there are both good and bad 6 speed autos.
dual clutch = a more complicated manual transmission that has the PCM/TCM controlling the clutch and shifter. so, to the driver, it's an automatic. ability to command shifts is not DCT specific, nor a requirement.