The DCT is two 3-speed manuals tied together with 2 clutches. Typically, one set controls the odd gears (1/3/5), while the other set controls the even number gears (2/4/6). One of them also runs the reverse gear.
The problems with DCT transmissions is that using the paddles is REQUIRED to get any decent behavior out of them because they're not quite the same thing as a normal automatic transmission. Even though it looks like there's a D like a regular automatic, even though it looks like P/R/N/D like a regular automatic, it's not. A DCT with no paddles is just downright awful. Neither of Ford's DCTs in the Fiesta and Focus have paddles, just D and L, for 6 gears. And you know they wouldn't DARE put a DCT in the Ecosport or Escape or any crossover or large car.
Ford sells the Fiesta overseas with a regular 4-speed automatic, and with all the recalls on the DCT, it would've been cheaper for Ford to just swap in the 4-speed auto. The Focus is available with a 6-speed automatic in the US, but only on the SE sedan with the 1.0T. Ford should use that automatic on all Focus models.
Honda makes a DCT with a torque converter on the TLX and RLX, and it's better than other DCTs, but it's still not as good as a regular automatic. They are still AWFUL in daily driving in the city.
Amalie makes a good DCT fluid at a great price when bought by the case, so if I had a DCT, I'd change the fluid every year if not every OCI. So special fluid is the least of your problems.
Theoretically the DCT is supposed to give you better mileage and be more efficient, but for this purpose, a CVT is best because it has an infinite number of gears/ratios. Also, regular torque converter automatics have gotten so good there's no need to put up with the many downsides of the DCT.
The DCT DOES NOT belong in normal regular economy cars and family cars. These poor designs should be restricted to high performance cars where the difference is actually meaningful and more likely to be driven in a way that actually benefits from a DCT.